










                         SENDMAILTM

              INSTALLATION AND OPERATION GUIDE

                        Eric Allman
                       Claus Assmann
                    Gregory Neil Shapiro
                      Proofpoint, Inc.


                 For Sendmail Version 8.16




     SendmailTM implements a general purpose internetwork
mail routing facility under the UNIX(R) operating system.
It is not tied to any one transport protocol -- its function
may be likened to a crossbar switch, relaying messages from
one domain into another.  In the process, it can do a
limited amount of message header editing to put the message
into a format that is appropriate for the receiving domain.
All of this is done under the control of a configuration
file.

     Due to the requirements of flexibility for sendmail,
the configuration file can seem somewhat unapproachable.
However, there are only a few basic configurations for most
sites, for which standard configuration files have been
supplied.  Most other configurations can be built by
adjusting an existing configuration file incrementally.

     Sendmail is based on RFC 821 (Simple Mail Transport
Protocol), RFC 822 (Internet Mail Headers Format), RFC 974
(MX routing), RFC 1123 (Internet Host Requirements), RFC
1413 (Identification server), RFC 1652 (SMTP 8BITMIME
Extension), RFC 1869 (SMTP Service Extensions), RFC 1870
(SMTP SIZE Extension), RFC 1891 (SMTP Delivery Status
Notifications), RFC 1892 (Multipart/Report), RFC 1893
(Enhanced Mail System Status Codes), RFC 1894 (Delivery
Status Notifications), RFC 1985 (SMTP Service Extension for
Remote Message Queue Starting), RFC 2033 (Local Message
Transmission Protocol), RFC 2034 (SMTP Service Extension for
____________________
   DISCLAIMER: This documentation is under modification.
   Sendmail  is  a  trademark of Proofpoint, Inc.  US Patent
Numbers 6865671, 6986037.




Sendmail Installation and Operation Guide           SMM:08-1







SMM:08-2           Sendmail Installation and Operation Guide


Returning Enhanced Error Codes), RFC 2045 (MIME), RFC 2476
(Message Submission), RFC 2487 (SMTP Service Extension for
Secure SMTP over TLS), RFC 2554 (SMTP Service Extension for
Authentication), RFC 2821 (Simple Mail Transfer Protocol),
RFC 2822 (Internet Message Format), RFC 2852 (Deliver By
SMTP Service Extension), and RFC 2920 (SMTP Service
Extension for Command Pipelining).  However, since sendmail
is designed to work in a wider world, in many cases it can
be configured to exceed these protocols.  These cases are
described herein.

     Although sendmail is intended to run without the need
for monitoring, it has a number of features that may be used
to monitor or adjust the operation under unusual
circumstances.  These features are described.

     Section one describes how to do a basic sendmail
installation.  Section two explains the day-to-day
information you should know to maintain your mail system.
If you have a relatively normal site, these two sections
should contain sufficient information for you to install
sendmail and keep it happy.  Section three has information
regarding the command line arguments.  Section four
describes some parameters that may be safely tweaked.
Section five contains the nitty-gritty information about the
configuration file.  This section is for masochists and
people who must write their own configuration file.  Section
six describes configuration that can be done at compile
time.  The appendixes give a brief but detailed explanation
of a number of features not described in the rest of the
paper.
































Sendmail Installation and Operation Guide           SMM:08-7


1.  BASIC INSTALLATION

        There are two basic steps to installing sendmail.
   First, you have to compile and install the binary.  If
   sendmail has already been ported to your operating system
   that should be simple.  Second, you must build a run-time
   configuration file.  This is a file that sendmail reads
   when it starts up that describes the mailers it knows
   about, how to parse addresses, how to rewrite the message
   header, and the settings of various options.  Although
   the configuration file can be quite complex, a
   configuration can usually be built using an M4-based
   configuration language.  Assuming you have the standard
   sendmail distribution, see cf/README for further
   information.

        The remainder of this section will describe the
   installation of sendmail assuming you can use one of the
   existing configurations and that the standard
   installation parameters are acceptable.  All pathnames
   and examples are given from the root of the sendmail
   subtree, normally /usr/src/usr.sbin/sendmail on 4.4BSD-
   based systems.

        Continue with the next section if you need/want to
   compile sendmail yourself.  If you have a running binary
   already on your system, you should probably skip to
   section 1.2.

   1.1.  Compiling Sendmail

           All sendmail source is in the sendmail
      subdirectory.  To compile sendmail, "cd" into the
      sendmail directory and type

          ./Build

      This will leave the binary in an appropriately named
      subdirectory, e.g., obj.BSD-OS.2.1.i386.  It works for
      multiple object versions compiled out of the same
      directory.

      1.1.1.  Tweaking the Build Invocation

              You can give parameters on the Build command.
         In most cases these are only used when the obj.*
         directory is first created.  To restart from
         scratch, use -c.  These commands include:

         -L libdirs
              A list of directories to search for libraries.












SMM:08-8           Sendmail Installation and Operation Guide


         -I incdirs
              A list of directories to search for include
              files.

         -E envar=value
              Set an environment variable to an indicated
              value before compiling.

         -c   Create a new obj.*  tree before running.

         -f siteconfig
              Read the indicated site configuration file.
              If this parameter is not specified, Build
              includes all of the files
              $BUILDTOOLS/Site/site.$oscf.m4 and
              $BUILDTOOLS/Site/site.config.m4, where
              $BUILDTOOLS is normally ../devtools and $oscf
              is the same name as used on the obj.*
              directory.  See below for a description of the
              site configuration file.

         -S   Skip auto-configuration.  Build will avoid
              auto-detecting libraries if this is set.  All
              libraries and map definitions must be
              specified in the site configuration file.

         Most other parameters are passed to the make
         program; for details see $BUILDTOOLS/README.

      1.1.2.  Creating a Site Configuration File

              See sendmail/README for various compilation
         flags that can be set, and devtools/README for
         details how to set them.

      1.1.3.  Tweaking the Makefile

              Sendmail supports two different formats for
         the local (on disk) version of databases, notably
         the aliases database.  At least one of these should
         be defined if at all possible.

         CDB       Constant DataBase (tinycdb).

         NDBM      The ``new DBM'' format, available on
                   nearly all systems around today.  This
                   was the preferred format prior to 4.4BSD.
                   It allows such complex things as multiple
                   databases and closing a currently open
                   database.

         NEWDB     The Berkeley DB package.  If you have
                   this, use it.  It allows long records,










Sendmail Installation and Operation Guide           SMM:08-9


                   multiple open databases, real in-memory
                   caching, and so forth.  You can define
                   this in conjunction with NDBM; if you do,
                   old alias databases are read, but when a
                   new database is created it will be in
                   NEWDB format.  As a nasty hack, if you
                   have NEWDB, NDBM, and NIS defined, and if
                   the alias file name includes the
                   substring "/yp/", sendmail will create
                   both new and old versions of the alias
                   file during a newalias command.  This is
                   required because the Sun NIS/YP system
                   reads the DBM version of the alias file.
                   It's ugly as sin, but it works.

         If neither of these are defined, sendmail reads the
         alias file into memory on every invocation.  This
         can be slow and should be avoided.  There are also
         several methods for remote database access:

         LDAP      Lightweight Directory Access Protocol.

         NIS       Sun's Network Information Services
                   (formerly YP).

         NISPLUS   Sun's NIS+ services.

         NETINFO   NeXT's NetInfo service.

         HESIOD    Hesiod service (from Athena).

         Other compilation flags are set in conf.h and
         should be predefined for you unless you are porting
         to a new environment.  For more options see
         sendmail/README.

      1.1.4.  Compilation and installation

              After making the local system configuration
         described above, You should be able to compile and
         install the system.  The script "Build" is the best
         approach on most systems:

             ./Build

         This will use uname(1) to create a custom Makefile
         for your environment.

              If you are installing in the standard places,
         you should be able to install using

             ./Build install











SMM:08-10          Sendmail Installation and Operation Guide


         This should install the binary in /usr/sbin and
         create links from /usr/bin/newaliases and
         /usr/bin/mailq to /usr/sbin/sendmail.  On most
         systems it will also format and install man pages.
         Notice: as of version 8.12 sendmail will no longer
         be installed set-user-ID root by default.  If you
         really want to use the old method, you can specify
         it as target:

             ./Build install-set-user-id


   1.2.  Configuration Files

           Sendmail cannot operate without a configuration
      file.  The configuration defines the mail delivery
      mechanisms understood at this site, how to access
      them, how to forward email to remote mail systems, and
      a number of tuning parameters.  This configuration
      file is detailed in the later portion of this
      document.

           The sendmail configuration can be daunting at
      first.  The world is complex, and the mail
      configuration reflects that.  The distribution
      includes an m4-based configuration package that hides
      a lot of the complexity.  See cf/README for details.

           Our configuration files are processed by m4 to
      facilitate local customization; the directory cf of
      the sendmail distribution directory contains the
      source files.  This directory contains several
      subdirectories:

      cf        Both site-dependent and site-independent
                descriptions of hosts.  These can be literal
                host names (e.g., "ucbvax.mc") when the
                hosts are gateways or more general
                descriptions (such as "generic-solaris2.mc"
                as a general description of an SMTP-
                connected host running Solaris 2.x.  Files
                ending .mc (``M4 Configuration'') are the
                input descriptions; the output is in the
                corresponding .cf file.  The general
                structure of these files is described below.

      domain    Site-dependent subdomain descriptions.
                These are tied to the way your organization
                wants to do addressing.  For example,
                domain/CS.Berkeley.EDU.m4 is our description
                for hosts in the CS.Berkeley.EDU subdomain.
                These are referenced using the DOMAIN m4
                macro in the .mc file.










Sendmail Installation and Operation Guide          SMM:08-11


      feature   Definitions of specific features that some
                particular host in your site might want.
                These are referenced using the FEATURE m4
                macro.  An example feature is use_cw_file
                (which tells sendmail to read an
                /etc/mail/local-host-names file on startup
                to find the set of local names).

      hack      Local hacks, referenced using the HACK m4
                macro.  Try to avoid these.  The point of
                having them here is to make it clear that
                they smell.

      m4        Site-independent m4(1) include files that
                have information common to all configuration
                files.  This can be thought of as a
                "#include" directory.

      mailer    Definitions of mailers, referenced using the
                MAILER m4 macro.  The mailer types that are
                known in this distribution are fax, local,
                smtp, uucp, and usenet.  For example, to
                include support for the UUCP-based mailers,
                use "MAILER(uucp)".

      ostype    Definitions describing various operating
                system environments (such as the location of
                support files).  These are referenced using
                the OSTYPE m4 macro.

      sh        Shell files used by the m4 build process.
                You shouldn't have to mess with these.

      siteconfig
                Local UUCP connectivity information.  This
                directory has been supplanted by the
                mailertable feature; any new configurations
                should use that feature to do UUCP (and
                other) routing.  The use of this directory
                is deprecated.

           If you are in a new domain (e.g., a company), you
      will probably want to create a cf/domain file for your
      domain.  This consists primarily of relay definitions
      and features you want enabled site-wide: for example,
      Berkeley's domain definition defines relays for BitNET
      and UUCP.  These are specific to Berkeley, and should
      be fully-qualified internet-style domain names.
      Please check to make certain they are reasonable for
      your domain.

           Subdomains at Berkeley are also represented in
      the cf/domain directory.  For example, the domain










SMM:08-12          Sendmail Installation and Operation Guide


      CS.Berkeley.EDU is the Computer Science subdomain,
      EECS.Berkeley.EDU is the Electrical Engineering and
      Computer Sciences subdomain, and S2K.Berkeley.EDU is
      the Sequoia 2000 subdomain.  You will probably have to
      add an entry to this directory to be appropriate for
      your domain.

           You will have to use or create .mc files in the
      cf/cf subdirectory for your hosts.  This is detailed
      in the cf/README file.

   1.3.  Details of Installation Files

           This subsection describes the files that comprise
      the sendmail installation.

      1.3.1.  /usr/sbin/sendmail

              The binary for sendmail is located in
         /usr/sbin[1].  It should be set-group-ID smmsp as
         described in sendmail/SECURITY.  For security
         reasons, /, /usr, and /usr/sbin should be owned by
         root, mode 0755[2].

      1.3.2.  /etc/mail/sendmail.cf

              This is the main configuration file for
         sendmail[3].  This is one of the two non-library
         file names compiled into sendmail[4], the other is
         /etc/mail/submit.cf.

____________________
   [1]This is usually /usr/sbin on 4.4BSD and newer systems;
many  systems install it in /usr/lib.  I understand it is in
/usr/ucblib on System V Release 4.
   [2]Some  vendors  ship  them owned by bin; this creates a
security hole that is  not  actually  related  to  sendmail.
Other  important  directories  that  should have restrictive
ownerships  and  permissions  are  /bin,   /usr/bin,   /etc,
/etc/mail, /usr/etc, /lib, and /usr/lib.
   [3]Actually,  the  pathname  varies  depending   on   the
operating  system;  /etc/mail  is  the  preferred directory.
Some older systems install it in  /usr/lib/sendmail.cf,  and
I've  also seen it in /usr/ucblib.  If you want to move this
file, add  -D_PATH_SENDMAILCF=\"/file/name\"  to  the  flags
passed   to  the  C  compiler.   Moving  this  file  is  not
recommended:  other  programs  and  scripts  know  of   this
location.
   [4]The  system  libraries  can  reference other files; in
particular, system library subroutines that  sendmail  calls
probably reference /etc/passwd and /etc/resolv.conf.












Sendmail Installation and Operation Guide          SMM:08-13


              The configuration file is normally created
         using the distribution files described above.  If
         you have a particularly unusual system
         configuration you may need to create a special
         version.  The format of this file is detailed in
         later sections of this document.

      1.3.3.  /etc/mail/submit.cf

              This is the configuration file for sendmail
         when it is used for initial mail submission, in
         which case it is also called ``Mail Submission
         Program'' (MSP) in contrast to ``Mail Transfer
         Agent'' (MTA).  Starting with version 8.12,
         sendmail uses one of two different configuration
         files based on its operation mode (or the new -A
         option).  For initial mail submission, i.e., if one
         of the options -bm (default), -bs, or -t is
         specified, submit.cf is used (if available), for
         other operations sendmail.cf is used.  Details can
         be found in sendmail/SECURITY.  submit.cf is
         shipped with sendmail (in cf/cf/) and is installed
         by default.  If changes to the configuration need
         to be made, start with cf/cf/submit.mc and follow
         the instruction in cf/README.

      1.3.4.  /usr/bin/newaliases

              The newaliases command should just be a link
         to sendmail:

             rm -f /usr/bin/newaliases
             ln -s /usr/sbin/sendmail /usr/bin/newaliases

         This can be installed in whatever search path you
         prefer for your system.

      1.3.5.  /usr/bin/hoststat

              The hoststat command should just be a link to
         sendmail, in a fashion similar to newaliases.  This
         command lists the status of the last mail
         transaction with all remote hosts.  The -v flag
         will prevent the status display from being
         truncated.  It functions only when the
         HostStatusDirectory option is set.

      1.3.6.  /usr/bin/purgestat

              This command is also a link to sendmail.  It
         flushes expired (Timeout.hoststatus) information
         that is stored in the HostStatusDirectory tree.











SMM:08-14          Sendmail Installation and Operation Guide


      1.3.7.  /var/spool/mqueue

              The directory /var/spool/mqueue should be
         created to hold the mail queue.  This directory
         should be mode 0700 and owned by root.

              The actual path of this directory is defined
         by the QueueDirectory option of the sendmail.cf
         file.  To use multiple queues, supply a value
         ending with an asterisk.  For example,
         /var/spool/mqueue/qd* will use all of the
         directories or symbolic links to directories
         beginning with `qd' in /var/spool/mqueue as queue
         directories.  Do not change the queue directory
         structure while sendmail is running.

              If these directories have subdirectories or
         symbolic links to directories named `qf', `df', and
         `xf', then these will be used for the different
         queue file types.  That is, the data files are
         stored in the `df' subdirectory, the transcript
         files are stored in the `xf' subdirectory, and all
         others are stored in the `qf' subdirectory.

              If shared memory support is compiled in,
         sendmail stores the available diskspace in a shared
         memory segment to make the values readily available
         to all children without incurring system overhead.
         In this case, only the daemon updates the data;
         i.e., the sendmail daemon creates the shared memory
         segment and deletes it if it is terminated.  To use
         this, sendmail must have been compiled with support
         for shared memory (-DSM_CONF_SHM) and the option
         SharedMemoryKey must be set.  Notice: do not use
         the same key for sendmail invocations with
         different queue directories or different queue
         group declarations.  Access to shared memory is not
         controlled by locks, i.e., there is a race
         condition when data in the shared memory is
         updated.  However, since operation of sendmail does
         not rely on the data in the shared memory, this
         does not negatively influence the behavior.

      1.3.8.  /var/spool/clientmqueue

              The directory /var/spool/clientmqueue should
         be created to hold the mail queue.  This directory
         should be mode 0770 and owned by user smmsp, group
         smmsp.

              The actual path of this directory is defined
         by the QueueDirectory option of the submit.cf file.











Sendmail Installation and Operation Guide          SMM:08-15


      1.3.9.  /var/spool/mqueue/.hoststat

              This is a typical value for the
         HostStatusDirectory option, containing one file per
         host that this sendmail has chatted with recently.
         It is normally a subdirectory of mqueue.

      1.3.10.  /etc/mail/aliases*

              The system aliases are held in
         "/etc/mail/aliases".  A sample is given in
         "sendmail/aliases" which includes some aliases
         which must be defined:

             cp sendmail/aliases /etc/mail/aliases
             edit /etc/mail/aliases

         You should extend this file with any aliases that
         are apropos to your system.

              Normally sendmail looks at a database version
         of the files, stored either in
         "/etc/mail/aliases.dir" and "/etc/mail/aliases.pag"
         or "/etc/mail/aliases.db" depending on which
         database package you are using.  The actual path of
         this file is defined in the AliasFile option of the
         sendmail.cf file.

              The permissions of the alias file and the
         database versions should be 0640 to prevent local
         denial of service attacks as explained in the top
         level README in the sendmail distribution.  If the
         permissions 0640 are used, be sure that only
         trusted users belong to the group assigned to those
         files.  Otherwise, files should not even be group
         readable.

      1.3.11.  /etc/rc or /etc/init.d/sendmail

              It will be necessary to start up the sendmail
         daemon when your system reboots.  This daemon
         performs two functions: it listens on the SMTP
         socket for connections (to receive mail from a
         remote system) and it processes the queue
         periodically to insure that mail gets delivered
         when hosts come up.

              If necessary, add the following lines to
         "/etc/rc" (or "/etc/rc.local" as appropriate) in
         the area where it is starting up the daemons on a
         BSD-base system, or on a System-V-based system in
         one of the startup files, typically
         "/etc/init.d/sendmail":










SMM:08-16          Sendmail Installation and Operation Guide


             if [ -f /usr/sbin/sendmail -a -f /etc/mail/sendmail.cf ]; then
                  (cd /var/spool/mqueue; rm -f xf*)
                  /usr/sbin/sendmail -bd -q30m &
                  echo -n ' sendmail' >/dev/console
             fi

         The "cd" and "rm" commands insure that all
         transcript files have been removed; extraneous
         transcript files may be left around if the system
         goes down in the middle of processing a message.
         The line that actually invokes sendmail has two
         flags: "-bd" causes it to listen on the SMTP port,
         and "-q30m" causes it to run the queue every half
         hour.

              Some people use a more complex startup script,
         removing zero length qf/hf/Qf files and df files
         for which there is no qf/hf/Qf file.  Note this is
         not advisable.  For example, see Figure 1 for an
         example of a complex script which does this clean
         up.

      1.3.12.  /etc/mail/helpfile

              This is the help file used by the SMTP HELP
         command.  It should be copied from
         "sendmail/helpfile":

             cp sendmail/helpfile /etc/mail/helpfile

         The actual path of this file is defined in the
         HelpFile option of the sendmail.cf file.

      1.3.13.  /etc/mail/statistics

              If you wish to collect statistics about your
         mail traffic, you should create the file
         "/etc/mail/statistics":

             cp /dev/null /etc/mail/statistics
             chmod 0600 /etc/mail/statistics

         This file does not grow.  It is printed with the
         program "mailstats/mailstats.c."  The actual path
         of this file is defined in the S option of the
         sendmail.cf file.

      1.3.14.  /usr/bin/mailq

              If sendmail is invoked as "mailq," it will
         simulate the -bp flag (i.e., sendmail will print
         the contents of the mail queue; see below).  This
         should be a link to /usr/sbin/sendmail.










Sendmail Installation and Operation Guide          SMM:08-17



____________________________________________________________

#!/bin/sh
# remove zero length qf/hf/Qf files
for qffile in qf* hf* Qf*
do
     if [ -r $qffile ]
     then
          if [ ! -s $qffile ]
          then
               echo -n " <zero: $qffile>" > /dev/console
               rm -f $qffile
          fi
     fi
done
# rename tf files to be qf if the qf does not exist
for tffile in tf*
do
     qffile=`echo $tffile | sed 's/t/q/'`
     if [ -r $tffile -a ! -f $qffile ]
     then
          echo -n " <recovering: $tffile>" > /dev/console
          mv $tffile $qffile
     else
          if [ -f $tffile ]
          then
               echo -n " <extra: $tffile>" > /dev/console
               rm -f $tffile
          fi
     fi
done
# remove df files with no corresponding qf/hf/Qf files
for dffile in df*
do
     qffile=`echo $dffile | sed 's/d/q/'`
     hffile=`echo $dffile | sed 's/d/h/'`
     Qffile=`echo $dffile | sed 's/d/Q/'`
     if [ -r $dffile -a ! -f $qffile -a ! -f $hffile -a ! -f $Qffile ]
     then
          echo -n " <incomplete: $dffile>" > /dev/console
          mv $dffile `echo $dffile | sed 's/d/D/'`
     fi
done
# announce files that have been saved during disaster recovery
for xffile in [A-Z]f*
do
     if [ -f $xffile ]
     then
          echo -n " <panic: $xffile>" > /dev/console
     fi
done











SMM:08-18          Sendmail Installation and Operation Guide


            Figure 1 -- A complex startup script
____________________________________________________________


      1.3.15.  sendmail.pid

              sendmail stores its current pid in the file
         specified by the PidFile option (default is
         _PATH_SENDMAILPID).  sendmail uses TempFileMode
         (which defaults to 0600) as the permissions of that
         file to prevent local denial of service attacks as
         explained in the top level README in the sendmail
         distribution.  If the file already exists, then it
         might be necessary to change the permissions
         accordingly, e.g.,

             chmod 0600 /var/run/sendmail.pid

         Note that as of version 8.13, this file is unlinked
         when sendmail exits.  As a result of this change, a
         script such as the following, which may have worked
         prior to 8.13, will no longer work:

             # stop & start sendmail
             PIDFILE=/var/run/sendmail.pid
             kill `head -1 $PIDFILE`
             `tail -1 $PIDFILE`

         because it assumes that the pidfile will still
         exist even after killing the process to which it
         refers.  Below is a script which will work
         correctly on both newer and older versions:

             # stop & start sendmail
             PIDFILE=/var/run/sendmail.pid
             pid=`head -1 $PIDFILE`
             cmd=`tail -1 $PIDFILE`
             kill $pid
             $cmd

         This is just an example script, it does not perform
         any error checks, e.g., whether the pidfile exists
         at all.

      1.3.16.  Map Files

              To prevent local denial of service attacks as
         explained in the top level README in the sendmail
         distribution, the permissions of map files created
         by makemap should be 0640.  The use of 0640 implies
         that only trusted users belong to the group
         assigned to those files.  If those files already
         exist, then it might be necessary to change the










Sendmail Installation and Operation Guide          SMM:08-19


         permissions accordingly, e.g.,

             cd /etc/mail
             chmod 0640 *.db *.pag *.dir


2.  NORMAL OPERATIONS

   2.1.  The System Log

           The system log is supported by the syslogd(8)
      program.  All messages from sendmail are logged under
      the LOG_MAIL facility[5].

      2.1.1.  Format

              Each line in the system log consists of a
         timestamp, the name of the machine that generated
         it (for logging from several machines over the
         local area network), the word "sendmail:", and a
         message[6].  Most messages are a sequence of
         name=value pairs.

              The two most common lines are logged when a
         message is processed.  The first logs the receipt
         of a message; there will be exactly one of these
         per message.  Some fields may be omitted if they do
         not contain interesting information.  Fields are:

         from      The envelope sender address.

         size      The size of the message in bytes.

         class     The class (i.e., numeric precedence) of
                   the message.

         pri       The initial message priority (used for
                   queue sorting).

         nrcpts    The number of envelope recipients for
                   this message (after aliasing and
                   forwarding).

         msgid     The message id of the message (from the
                   header).

____________________
   [5]Except on Ultrix, which does not support facilities in
the syslog.
   [6]This format may  vary  slightly  if  your  vendor  has
changed the syntax.












SMM:08-20          Sendmail Installation and Operation Guide


         bodytype  The message body type (7BIT or 8BITMIME),
                   as determined from the envelope.

         proto     The protocol used to receive this message
                   (e.g., ESMTP or UUCP)

         daemon    The daemon name from the
                   DaemonPortOptions setting.

         relay     The machine from which it was received.

         There is also one line logged per delivery attempt
         (so there can be several per message if delivery is
         deferred or there are multiple recipients).  Fields
         are:

         to        A comma-separated list of the recipients
                   to this mailer.

         ctladdr   The ``controlling user'', that is, the
                   name of the user whose credentials we use
                   for delivery.

         delay     The total delay between the time this
                   message was received and the current
                   delivery attempt.

         xdelay    The amount of time needed in this
                   delivery attempt (normally indicative of
                   the speed of the connection).

         mailer    The name of the mailer used to deliver to
                   this recipient.

         relay     The name of the host that actually
                   accepted (or rejected) this recipient.

         dsn       The enhanced error code (RFC 2034) if
                   available.

         stat      The delivery status.

         Not all fields are present in all messages; for
         example, the relay is usually not listed for local
         deliveries.

      2.1.2.  Levels

              If you have syslogd(8) or an equivalent
         installed, you will be able to do logging.  There
         is a large amount of information that can be
         logged.  The log is arranged as a succession of
         levels.  At the lowest level only extremely strange










Sendmail Installation and Operation Guide          SMM:08-21


         situations are logged.  At the highest level, even
         the most mundane and uninteresting events are
         recorded for posterity.  As a convention, log
         levels under ten are considered generally "useful;"
         log levels above 64 are reserved for debugging
         purposes.  Levels from 11-64 are reserved for
         verbose information that some sites might want.

              A complete description of the log levels is
         given in section ``Log Level''.

   2.2.  Dumping State

           You can ask sendmail to log a dump of the open
      files and the connection cache by sending it a SIGUSR1
      signal.  The results are logged at LOG_DEBUG priority.

   2.3.  The Mail Queues

           Mail messages may either be delivered immediately
      or be held for later delivery.  Held messages are
      placed into a holding directory called a mail queue.

           A mail message may be queued for these reasons:

       + If a mail message is temporarily undeliverable, it
         is queued and delivery is attempted later.  If the
         message is addressed to multiple recipients, it is
         queued only for those recipients to whom delivery
         is not immediately possible.
       + If the SuperSafe option is set to true, all mail
         messages are queued while delivery is attempted.
       + If the DeliveryMode option is set to queue-only or
         defer, all mail is queued, and no immediate
         delivery is attempted.
       + If the load average becomes higher than the value
         of the QueueLA option and the QueueFactor (q)
         option divided by the difference in the current
         load average and the QueueLA option plus one is
         less than the priority of the message, messages are
         queued rather than immediately delivered.
       + One or more addresses are marked as expensive and
         delivery is postponed until the next queue run or
         one or more address are marked as held via mailer
         which uses the hold mailer flag.
       + The mail message has been marked as quarantined via
         a mail filter or rulesets.

      2.3.1.  Queue Groups and Queue Directories

              There are one or more mail queues.  Each mail
         queue belongs to a queue group.  There is always a
         default queue group that is called ``mqueue''










SMM:08-22          Sendmail Installation and Operation Guide


         (which is where messages go by default unless
         otherwise specified).  The directory or directories
         which comprise the default queue group are
         specified by the QueueDirectory option.  There are
         zero or more additional named queue groups declared
         using the Q command in the configuration file.

              By default, a queued message is placed in the
         queue group associated with the first recipient in
         the recipient list.  A recipient address is mapped
         to a queue group as follows.  First, if there is a
         ruleset called ``queuegroup'', and if this ruleset
         maps the address to a queue group name, then that
         queue group is chosen.  That is, the argument for
         the ruleset is the recipient address (i.e., the
         address part of the resolved triple) and the result
         should be $# followed by the name of a queue group.
         Otherwise, if the mailer associated with the
         address specifies a queue group, then that queue
         group is chosen.  Otherwise, the default queue
         group is chosen.

              A message with multiple recipients will be
         split if different queue groups are chosen by the
         mapping of recipients to queue groups.

              When a message is placed in a queue group, and
         the queue group has more than one queue, a queue is
         selected randomly.

              If a message with multiple recipients is
         placed into a queue group with the 'r' option
         (maximum number of recipients per message) set to a
         positive value N, and if there are more than N
         recipients in the message, then the message will be
         split into multiple messages, each of which have at
         most N recipients.

              Notice: if multiple queue groups are used, do
         not move queue files around, e.g., into a different
         queue directory.  This may have weird effects and
         can cause mail not to be delivered.  Queue files
         and directories should be treated as opaque and
         should not be manipulated directly.

      2.3.2.  Queue Runs

              sendmail has two different ways to process the
         queue(s).  The first one is to start queue runners
         after certain intervals (``normal'' queue runners),
         the second one is to keep queue runner processes
         around (``persistent'' queue runners).  How to
         select either of these types is discussed in the










Sendmail Installation and Operation Guide          SMM:08-23


         appendix ``COMMAND LINE FLAGS''.  Persistent queue
         runners have the advantage that no new processes
         need to be spawned at certain intervals; they just
         sleep for a specified time after they finished a
         queue run.  Another advantage of persistent queue
         runners is that only one process belonging to a
         workgroup (a workgroup is a set of queue groups)
         collects the data for a queue run and then multiple
         queue runner may go ahead using that data.  This
         can significantly reduce the disk I/O necessary to
         read the queue files compared to starting multiple
         queue runners directly.  Their disadvantage is that
         a new queue run is only started after all queue
         runners belonging to a group finished their tasks.
         In case one of the queue runners tries delivery to
         a slow recipient site at the end of a queue run,
         the next queue run may be substantially delayed.
         In general this should be smoothed out due to the
         distribution of those slow jobs, however, for sites
         with small number of queue entries this might
         introduce noticeable delays.  In general,
         persistent queue runners are only useful for sites
         with big queues.

      2.3.3.  Manual Intervention

              Under normal conditions the mail queue will be
         processed transparently.  However, you may find
         that manual intervention is sometimes necessary.
         For example, if a major host is down for a period
         of time the queue may become clogged.  Although
         sendmail ought to recover gracefully when the host
         comes up, you may find performance unacceptably bad
         in the meantime.  In that case you want to check
         the content of the queue and manipulate it as
         explained in the next two sections.

      2.3.4.  Printing the queue

              The contents of the queue(s) can be printed
         using the mailq command (or by specifying the -bp
         flag to sendmail):

             mailq

         This will produce a listing of the queue id's, the
         size of the message, the date the message entered
         the queue, and the sender and recipients.  If
         shared memory support is compiled in, the flag -bP
         can be used to print the number of entries in the
         queue(s), provided a process updates the data.
         However, as explained earlier, the output might be
         slightly wrong, since access to the shared memory










SMM:08-24          Sendmail Installation and Operation Guide


         is not locked.  For example, ``unknown number of
         entries'' might be shown.  The internal counters
         are updated after each queue run to the correct
         value again.

      2.3.5.  Forcing the queue

              Sendmail should run the queue automatically at
         intervals.  When using multiple queues, a separate
         process will by default be created to run each of
         the queues unless the queue run is initiated by a
         user with the verbose flag.  The algorithm is to
         read and sort the queue, and then to attempt to
         process all jobs in order.  When it attempts to run
         the job, sendmail first checks to see if the job is
         locked.  If so, it ignores the job.

              There is no attempt to insure that only one
         queue processor exists at any time, since there is
         no guarantee that a job cannot take forever to
         process (however, sendmail does include heuristics
         to try to abort jobs that are taking absurd amounts
         of time; technically, this violates RFC 821, but is
         blessed by RFC 1123).  Due to the locking
         algorithm, it is impossible for one job to freeze
         the entire queue.  However, an uncooperative
         recipient host or a program recipient that never
         returns can accumulate many processes in your
         system.  Unfortunately, there is no completely
         general way to solve this.

              In some cases, you may find that a major host
         going down for a couple of days may create a
         prohibitively large queue.  This will result in
         sendmail spending an inordinate amount of time
         sorting the queue.  This situation can be fixed by
         moving the queue to a temporary place and creating
         a new queue.  The old queue can be run later when
         the offending host returns to service.

              To do this, it is acceptable to move the
         entire queue directory:

             cd /var/spool
             mv mqueue omqueue; mkdir mqueue; chmod 0700 mqueue

         You should then kill the existing daemon (since it
         will still be processing in the old queue
         directory) and create a new daemon.

              To run the old mail queue, issue the following
         command:











Sendmail Installation and Operation Guide          SMM:08-25


             /usr/sbin/sendmail -C /etc/mail/queue.cf -q

         The -C flag specifies an alternate configuration
         file queue.cf which should refer to the moved queue
         directory

             O QueueDirectory=/var/spool/omqueue

         and the -q flag says to just run every job in the
         queue.  You can also specify the moved queue
         directory on the command line

             /usr/sbin/sendmail -oQ/var/spool/omqueue -q

         but this requires that you do not have queue groups
         in the configuration file, because those are not
         subdirectories of the moved directory.  See the
         section about ``Queue Group Declaration'' for
         details; you most likely need a different
         configuration file to correctly deal with this
         problem.  However, a proper configuration of queue
         groups should avoid filling up queue directories,
         so you shouldn't run into this problem.  If you
         have a tendency toward voyeurism, you can use the
         -v flag to watch what is going on.

              When the queue is finally emptied, you can
         remove the directory:

             rmdir /var/spool/omqueue


      2.3.6.  Quarantined Queue Items

              It is possible to "quarantine" mail messages,
         otherwise known as envelopes.  Envelopes (queue
         files) are stored but not considered for delivery
         or display unless the "quarantine" state of the
         envelope is undone or delivery or display of
         quarantined items is requested.  Quarantined
         messages are tagged by using a different name for
         the queue file, 'hf' instead of 'qf', and by adding
         the quarantine reason to the queue file.

              Delivery or display of quarantined items can
         be requested using the -qQ flag to sendmail or
         mailq.  Additionally, messages already in the queue
         can be quarantined or unquarantined using the new
         -Q flag to sendmail.  For example,

             sendmail -Qreason -q[!][I|R|S][matchstring]

         Quarantines the normal queue items matching the










SMM:08-26          Sendmail Installation and Operation Guide


         criteria specified by the -q[!][I|R|S][matchstring]
         using the reason given on the -Q flag.  Likewise,

             sendmail -qQ -Q[reason] -q[!][I|R|S|Q][matchstring]

         Change the quarantine reason for the quarantined
         items matching the criteria specified by the
         -q[!][I|R|S|Q][matchstring] using the reason given
         on the -Q flag.  If there is no reason,
          unquarantine the matching items and make them
         normal queue items.  Note that the -qQ flag tells
         sendmail to operate on quarantined items instead of
         normal items.

   2.4.  Disk Based Connection Information

           Sendmail stores a large amount of information
      about each remote system it has connected to in
      memory. It is possible to preserve some of this
      information on disk as well, by using the
      HostStatusDirectory option, so that it may be shared
      between several invocations of sendmail.  This allows
      mail to be queued immediately or skipped during a
      queue run if there has been a recent failure in
      connecting to a remote machine.  Note: information
      about a remote system is stored in a file whose
      pathname consists of the components of the hostname in
      reverse order.  For example, the information for
      host.example.com is stored in com./example./host.  For
      top-level domains like com this can create a large
      number of subdirectories which on some filesystems can
      exhaust some limits.  Moreover, the performance of
      lookups in directory with thousands of entries can be
      fairly slow depending on the filesystem
      implementation.

           Additionally enabling SingleThreadDelivery has
      the added effect of single-threading mail delivery to
      a destination.  This can be quite helpful if the
      remote machine is running an SMTP server that is
      easily overloaded or cannot accept more than a single
      connection at a time, but can cause some messages to
      be punted to a future queue run.  It also applies to
      all hosts, so setting this because you have one
      machine on site that runs some software that is easily
      overrun can cause mail to other hosts to be slowed
      down.  If this option is set, you probably want to set
      the MinQueueAge option as well and run the queue
      fairly frequently; this way jobs that are skipped
      because another sendmail is talking to the same host
      will be tried again quickly rather than being delayed
      for a long time.











Sendmail Installation and Operation Guide          SMM:08-27


           The disk based host information is stored in a
      subdirectory of the mqueue directory called
      .hoststat[7].  Removing this directory and its
      subdirectories has an effect similar to the purgestat
      command and is completely safe.  However, purgestat
      only removes expired (Timeout.hoststatus) data.  The
      information in these directories can be perused with
      the hoststat command, which will indicate the host
      name, the last access, and the status of that access.
      An asterisk in the left most column indicates that a
      sendmail process currently has the host locked for
      mail delivery.

           The disk based connection information is treated
      the same way as memory based connection information
      for the purpose of timeouts.  By default, information
      about host failures is valid for 30 minutes.  This can
      be adjusted with the Timeout.hoststatus option.

           The connection information stored on disk may be
      expired at any time with the purgestat command or by
      invoking sendmail with the -bH switch.  The connection
      information may be viewed with the hoststat command or
      by invoking sendmail with the -bh switch.

   2.5.  The Service Switch

           The implementation of certain system services
      such as host and user name lookup is controlled by the
      service switch.  If the host operating system supports
      such a switch, and sendmail knows about it, sendmail
      will use the native version.  Ultrix, Solaris, and DEC
      OSF/1 are examples of such systems[8].

           If the underlying operating system does not
      support a service switch (e.g., SunOS 4.X, HP-UX, BSD)
      then sendmail will provide a stub implementation.  The
      ServiceSwitchFile option points to the name of a file
      that has the service definitions.  Each line has the
      name of a service and the possible implementations of
      that service.  For example, the file:

          hosts     dns files nis
          aliases   files nis
____________________
   [7]This is the usual  value  of  the  HostStatusDirectory
option;  it  can,  of  course,  go anywhere you like in your
filesystem.
   [8]HP-UX 10 has service switch  support,  but  since  the
APIs  are apparently not available in the libraries sendmail
does not use the native service switch in this release.












SMM:08-28          Sendmail Installation and Operation Guide


      will ask sendmail to look for hosts in the Domain Name
      System first.  If the requested host name is not
      found, it tries local files, and if that fails it
      tries NIS.  Similarly, when looking for aliases it
      will try the local files first followed by NIS.

           Notice: since sendmail must access MX records for
      correct operation, it will use DNS if it is configured
      in the ServiceSwitchFile file.  Hence an entry like

          hosts     files dns

      will not avoid DNS lookups even if a host can be found
      in /etc/hosts.

           Service switches are not completely integrated.
      For example, despite the fact that the host entry
      listed in the above example specifies to look in NIS,
      on SunOS this won't happen because the system
      implementation of gethostbyname(3) doesn't understand
      this.

   2.6.  The Alias Database

           After recipient addresses are read from the SMTP
      connection or command line they are parsed by ruleset
      0, which must resolve to a {mailer, host, address}
      triple.  If the flags selected by the mailer include
      the A (aliasable) flag, the address part of the triple
      is looked up as the key (i.e., the left hand side) in
      the alias database.  If there is a match, the address
      is deleted from the send queue and all addresses on
      the right hand side of the alias are added in place of
      the alias that was found.  This is a recursive
      operation, so aliases found in the right hand side of
      the alias are similarly expanded.

           The alias database exists in two forms.  One is a
      text form, maintained in the file /etc/mail/aliases.
      The aliases are of the form

          name: name1, name2, ...

      Only local names may be aliased; e.g.,

          eric@prep.ai.MIT.EDU: eric@CS.Berkeley.EDU

      will not have the desired effect (except on















Sendmail Installation and Operation Guide          SMM:08-29


      prep.ai.MIT.EDU, and they probably don't want me)[9].
      Aliases may be continued by starting any continuation
      lines with a space or a tab or by putting a backslash
      directly before the newline.  Blank lines and lines
      beginning with a sharp sign ("#") are comments.

           The second form is processed by the ndbm(3)[10]
      or the Berkeley DB library.  This form is in the file
      /etc/mail/aliases.db (if using NEWDB) or
      /etc/mail/aliases.dir and /etc/mail/aliases.pag (if
      using NDBM).  This is the form that sendmail actually
      uses to resolve aliases.  This technique is used to
      improve performance.

           The control of search order is actually set by
      the service switch.  Essentially, the entry

          O AliasFile=switch:aliases

      is always added as the first alias entry; also, the
      first alias file name without a class (e.g., without
      "nis:" on the front) will be used as the name of the
      file for a ``files'' entry in the aliases switch.  For
      example, if the configuration file contains

          O AliasFile=/etc/mail/aliases

      and the service switch contains

          aliases   nis files nisplus

      then aliases will first be searched in the NIS
      database, then in /etc/mail/aliases, then in the NIS+
      database.

           You can also use NIS-based alias files.  For
      example, the specification:

          O AliasFile=/etc/mail/aliases
          O AliasFile=nis:mail.aliases@my.nis.domain

      will first search the /etc/mail/aliases file and then
      the map named "mail.aliases" in "my.nis.domain".
      Warning: if you build your own NIS-based alias files,
      be sure to provide the -l flag to makedbm(8) to map
      upper case letters in the keys to lower case;
      otherwise, aliases with upper case letters in their
____________________
   [9]Actually, any mailer that has the `A' mailer flag  set
will  permit aliasing; this is normally limited to the local
mailer.
   [10]The gdbm package does not work.











SMM:08-30          Sendmail Installation and Operation Guide


      names won't match incoming addresses.

           Additional flags can be added after the colon
      exactly like a K line -- for example:

          O AliasFile=nis:-N mail.aliases@my.nis.domain

      will search the appropriate NIS map and always include
      null bytes in the key.  Also:

          O AliasFile=nis:-f mail.aliases@my.nis.domain

      will prevent sendmail from downcasing the key before
      the alias lookup.

      2.6.1.  Rebuilding the alias database

              The hash or dbm version of the database may be
         rebuilt explicitly by executing the command

             newaliases

         This is equivalent to giving sendmail the -bi flag:

             /usr/sbin/sendmail -bi


              If you have multiple aliases databases
         specified, the -bi flag rebuilds all the database
         types it understands (for example, it can rebuild
         NDBM databases but not NIS databases).

      2.6.2.  Potential problems

              There are a number of problems that can occur
         with the alias database.  They all result from a
         sendmail process accessing the DBM version while it
         is only partially built.  This can happen under two
         circumstances: One process accesses the database
         while another process is rebuilding it, or the
         process rebuilding the database dies (due to being
         killed or a system crash) before completing the
         rebuild.

              Sendmail has three techniques to try to
         relieve these problems.  First, it ignores
         interrupts while rebuilding the database; this
         avoids the problem of someone aborting the process
         leaving a partially rebuilt database.  Second, it
         locks the database source file during the rebuild
         -- but that may not work over NFS or if the file is
         unwritable.  Third, at the end of the rebuild it
         adds an alias of the form










Sendmail Installation and Operation Guide          SMM:08-31


             @: @

         (which is not normally legal).  Before sendmail
         will access the database, it checks to insure that
         this entry exists[11].

      2.6.3.  List owners

              If an error occurs on sending to a certain
         address, say "x", sendmail will look for an alias
         of the form "owner-x" to receive the errors.  This
         is typically useful for a mailing list where the
         submitter of the list has no control over the
         maintenance of the list itself; in this case the
         list maintainer would be the owner of the list.
         For example:

             unix-wizards: eric@ucbarpa, wnj@monet, nosuchuser,
                  sam@matisse
             owner-unix-wizards: unix-wizards-request
             unix-wizards-request: eric@ucbarpa

         would cause "eric@ucbarpa" to get the error that
         will occur when someone sends to unix-wizards due
         to the inclusion of "nosuchuser" on the list.

              List owners also cause the envelope sender
         address to be modified.  The contents of the owner
         alias are used if they point to a single user,
         otherwise the name of the alias itself is used.
         For this reason, and to obey Internet conventions,
         the "owner-" address normally points at the
         "-request" address; this causes messages to go out
         with the typical Internet convention of using
         ``list-request'' as the return address.

   2.7.  User Information Database

           This option is deprecated, use virtusertable and
      genericstable instead as explained in cf/README.  If
      you have a version of sendmail with the user
      information database compiled in, and you have
      specified one or more databases using the U option,
      the databases will be searched for a user:maildrop
      entry.  If found, the mail will be sent to the
      specified address.

____________________
   [11]The AliasWait option is required in the configuration
for  this  action  to  occur.   This  should   normally   be
specified.












SMM:08-32          Sendmail Installation and Operation Guide


   2.8.  Per-User Forwarding (.forward Files)

           As an alternative to the alias database, any user
      may put a file with the name ".forward" in his or her
      home directory.  If this file exists, sendmail
      redirects mail for that user to the list of addresses
      listed in the .forward file.  Note that aliases are
      fully expanded before forward files are referenced.
      For example, if the home directory for user "mckusick"
      has a .forward file with contents:

          mckusick@ernie
          kirk@calder

      then any mail arriving for "mckusick" will be
      redirected to the specified accounts.

           Actually, the configuration file defines a
      sequence of filenames to check.  By default, this is
      the user's .forward file, but can be defined to be
      more generally using the ForwardPath option.  If you
      change this, you will have to inform your user base of
      the change; .forward is pretty well incorporated into
      the collective subconscious.

   2.9.  Special Header Lines

           Several header lines have special interpretations
      defined by the configuration file.  Others have
      interpretations built into sendmail that cannot be
      changed without changing the code.  These built-ins
      are described here.

      2.9.1.  Errors-To:

              If errors occur anywhere during processing,
         this header will cause error messages to go to the
         listed addresses.  This is intended for mailing
         lists.

              The Errors-To: header was created in the bad
         old days when UUCP didn't understand the
         distinction between an envelope and a header; this
         was a hack to provide what should now be passed as
         the envelope sender address.  It should go away.
         It is only used if the UseErrorsTo option is set.

              The Errors-To: header is officially deprecated
         and will go away in a future release.














Sendmail Installation and Operation Guide          SMM:08-33


      2.9.2.  Apparently-To:

              RFC 822 requires at least one recipient field
         (To:, Cc:, or Bcc: line) in every message.  If a
         message comes in with no recipients listed in the
         message then sendmail will adjust the header based
         on the "NoRecipientAction" option.  One of the
         possible actions is to add an "Apparently-To:"
         header line for any recipients it is aware of.

              The Apparently-To: header is non-standard and
         is both deprecated and strongly discouraged.

      2.9.3.  Precedence

              The Precedence: header can be used as a crude
         control of message priority.  It tweaks the sort
         order in the queue and can be configured to change
         the message timeout values.  The precedence of a
         message also controls how delivery status
         notifications (DSNs) are processed for that
         message.

   2.10.  IDENT Protocol Support

           Sendmail supports the IDENT protocol as defined
      in RFC 1413.  Note that the RFC states a client should
      wait at least 30 seconds for a response.  The default
      Timeout.ident is 5 seconds as many sites have adopted
      the practice of dropping IDENT queries.  This has lead
      to delays processing mail.  Although this enhances
      identification of the author of an email message by
      doing a ``call back'' to the originating system to
      include the owner of a particular TCP connection in
      the audit trail it is in no sense perfect; a
      determined forger can easily spoof the IDENT protocol.
      The following description is excerpted from RFC 1413:

           6.  Security Considerations

           The information returned by this protocol is at
           most as trustworthy as the host providing it OR
           the organization operating the host.  For
           example, a PC in an open lab has few if any
           controls on it to prevent a user from having this
           protocol return any identifier the user wants.
           Likewise, if the host has been compromised the
           information returned may be completely erroneous
           and misleading.

           The Identification Protocol is not intended as an
           authorization or access control protocol.  At
           best, it provides some additional auditing










SMM:08-34          Sendmail Installation and Operation Guide


           information with respect to TCP connections.  At
           worst, it can provide misleading, incorrect, or
           maliciously incorrect information.

           The use of the information returned by this
           protocol for other than auditing is strongly
           discouraged.  Specifically, using Identification
           Protocol information to make access control
           decisions - either as the primary method (i.e.,
           no other checks) or as an adjunct to other
           methods may result in a weakening of normal host
           security.

           An Identification server may reveal information
           about users, entities, objects or processes which
           might normally be considered private.  An
           Identification server provides service which is a
           rough analog of the CallerID services provided by
           some phone companies and many of the same privacy
           considerations and arguments that apply to the
           CallerID service apply to Identification.  If you
           wouldn't run a "finger" server due to privacy
           considerations you may not want to run this
           protocol.

      In some cases your system may not work properly with
      IDENT support due to a bug in the TCP/IP
      implementation.  The symptoms will be that for some
      hosts the SMTP connection will be closed almost
      immediately.  If this is true or if you do not want to
      use IDENT, you should set the IDENT timeout to zero;
      this will disable the IDENT protocol.

3.  ARGUMENTS

        The complete list of arguments to sendmail is
   described in detail in Appendix A.  Some important
   arguments are described here.

   3.1.  Queue Interval

           The amount of time between forking a process to
      run through the queue is defined by the -q flag.  If
      you run with delivery mode set to i or b this can be
      relatively large, since it will only be relevant when
      a host that was down comes back up.  If you run in q
      mode it should be relatively short, since it defines
      the maximum amount of time that a message may sit in
      the queue.  (See also the MinQueueAge option.)

           RFC 1123 section 5.3.1.1 says that this value
      should be at least 30 minutes (although that probably
      doesn't make sense if you use ``queue-only'' mode).










Sendmail Installation and Operation Guide          SMM:08-35


           Notice: the meaning of the interval time depends
      on whether normal queue runners or persistent queue
      runners are used.  For the former, it is the time
      between subsequent starts of a queue run.  For the
      latter, it is the time sendmail waits after a
      persistent queue runner has finished its work to start
      the next one.  Hence for persistent queue runners this
      interval should be very low, typically no more than
      two minutes.

   3.2.  Daemon Mode

           If you allow incoming mail over an IPC
      connection, you should have a daemon running.  This
      should be set by your /etc/rc file using the -bd flag.
      The -bd flag and the -q flag may be combined in one
      call:

          /usr/sbin/sendmail -bd -q30m


           An alternative approach is to invoke sendmail
      from inetd(8) (use the -bs -Am flags to ask sendmail
      to speak SMTP on its standard input and output and to
      run as MTA).  This works and allows you to wrap
      sendmail in a TCP wrapper program, but may be a bit
      slower since the configuration file has to be re-read
      on every message that comes in.  If you do this, you
      still need to have a sendmail running to flush the
      queue:

          /usr/sbin/sendmail -q30m


   3.3.  Forcing the Queue

           In some cases you may find that the queue has
      gotten clogged for some reason.  You can force a queue
      run using the -q flag (with no value).  It is
      entertaining to use the -v flag (verbose) when this is
      done to watch what happens:

          /usr/sbin/sendmail -q -v


           You can also limit the jobs to those with a
      particular queue identifier, recipient, sender,
      quarantine reason, or queue group using one of the
      queue modifiers.  For example, "-qRberkeley" restricts
      the queue run to jobs that have the string "berkeley"
      somewhere in one of the recipient addresses.
      Similarly, "-qSstring" limits the run to particular
      senders, "-qIstring" limits it to particular queue










SMM:08-36          Sendmail Installation and Operation Guide


      identifiers, and "-qQstring" limits it to particular
      quarantined reasons and only operated on quarantined
      queue items, and "-qGstring" limits it to a particular
      queue group.  The named queue group will be run even
      if it is set to have 0 runners.  You may also place an
      !  before the I or R or S or Q to indicate that jobs
      are limited to not including a particular queue
      identifier, recipient or sender.  For example,
      "-q!Rseattle" limits the queue run to jobs that do not
      have the string "seattle" somewhere in one of the
      recipient addresses.  Should you need to terminate the
      queue jobs currently active then a SIGTERM to the
      parent of the process (or processes) will cleanly stop
      the jobs.

   3.4.  Debugging

           There are a fairly large number of debug flags
      built into sendmail.  Each debug flag has a category
      and a level.  Higher levels increase the level of
      debugging activity; in most cases, this means to print
      out more information.  The convention is that levels
      greater than nine are "absurd," i.e., they print out
      so much information that you wouldn't normally want to
      see them except for debugging that particular piece of
      code.

           You should never run a production sendmail server
      in debug mode.  Many of the debug flags will result in
      debug output being sent over the SMTP channel unless
      the option -D is used.  This will confuse many mail
      programs.  However, for testing purposes, it can be
      useful when sending mail manually via telnet to the
      port you are using while debugging.

           A debug category is either an integer, like 42,
      or a name, like ANSI.  You can specify a range of
      numeric debug categories using the syntax 17-42.  You
      can specify a set of named debug categories using a
      glob pattern like "sm_trace_*".  At present, only "*"
      and "?"  are supported in these glob patterns.

           Debug flags are set using the -d option; the
      syntax is:

          debug-flag:        -d debug-list
          debug-list:        debug-option [ , debug-option ]*
          debug-option:      debug-categories [ . debug-level ]
          debug-categories:  integer | integer - integer | category-pattern
          category-pattern:  [a-zA-Z_*?][a-zA-Z0-9_*?]*
          debug-level:       integer

      where spaces are for reading ease only.  For example,










Sendmail Installation and Operation Guide          SMM:08-37


          -d12               Set category 12 to level 1
          -d12.3             Set category 12 to level 3
          -d3-17             Set categories 3 through 17 to level 1
          -d3-17.4           Set categories 3 through 17 to level 4
          -dANSI             Set category ANSI to level 1
          -dsm_trace_*.3     Set all named categories matching sm_trace_* to level 3

      For a complete list of the available debug flags you
      will have to look at the code and the TRACEFLAGS file
      in the sendmail distribution (they are too dynamic to
      keep this document up to date).  For a list of named
      debug categories in the sendmail binary, use

          ident /usr/sbin/sendmail | grep Debug


   3.5.  Changing the Values of Options

           Options can be overridden using the -o or -O
      command line flags.  For example,

          /usr/sbin/sendmail -oT2m

      sets the T (timeout) option to two minutes for this
      run only; the equivalent line using the long option
      name is

          /usr/sbin/sendmail -OTimeout.queuereturn=2m


           Some options have security implications.
      Sendmail allows you to set these, but relinquishes its
      set-user-ID or set-group-ID permissions
      thereafter[12].

   3.6.  Trying a Different Configuration File

           An alternative configuration file can be
      specified using the -C flag; for example,

          /usr/sbin/sendmail -Ctest.cf -oQ/tmp/mqueue

      uses the configuration file test.cf instead of the
      default /etc/mail/sendmail.cf.  If the -C flag has no
      value it defaults to sendmail.cf in the current
      directory.
____________________
   [12]That is, it sets its effective uid to the  real  uid;
thus,  if  you are executing as root, as from root's crontab
file or during system  startup  the  root  permissions  will
still be honored.












SMM:08-38          Sendmail Installation and Operation Guide


           Sendmail gives up set-user-ID root permissions
      (if it has been installed set-user-ID root) when you
      use this flag, so it is common to use a publicly
      writable directory (such as /tmp) as the queue
      directory (QueueDirectory or Q option) while testing.

   3.7.  Logging Traffic

           Many SMTP implementations do not fully implement
      the protocol.  For example, some personal computer
      based SMTPs do not understand continuation lines in
      reply codes.  These can be very hard to trace.  If you
      suspect such a problem, you can set traffic logging
      using the -X flag.  For example,

          /usr/sbin/sendmail -X /tmp/traffic -bd

      will log all traffic in the file /tmp/traffic.

           This logs a lot of data very quickly and should
      NEVER be used during normal operations.  After
      starting up such a daemon, force the errant
      implementation to send a message to your host.  All
      message traffic in and out of sendmail, including the
      incoming SMTP traffic, will be logged in this file.

   3.8.  Testing Configuration Files

           When you build a configuration table, you can do
      a certain amount of testing using the "test mode" of
      sendmail.  For example, you could invoke sendmail as:

          sendmail -bt -Ctest.cf

      which would read the configuration file "test.cf" and
      enter test mode.  In this mode, you enter lines of the
      form:

          rwset address

      where rwset is the rewriting set you want to use and
      address is an address to apply the set to.  Test mode
      shows you the steps it takes as it proceeds, finally
      showing you the address it ends up with.  You may use
      a comma separated list of rwsets for sequential
      application of rules to an input.  For example:

          3,1,21,4 monet:bollard

      first applies ruleset three to the input
      "monet:bollard."  Ruleset one is then applied to the
      output of ruleset three, followed similarly by
      rulesets twenty-one and four.










Sendmail Installation and Operation Guide          SMM:08-39


           If you need more detail, you can also use the
      "-d21" flag to turn on more debugging.  For example,

          sendmail -bt -d21.99

      turns on an incredible amount of information; a single
      word address is probably going to print out several
      pages worth of information.

           You should be warned that internally, sendmail
      applies ruleset 3 to all addresses.  In test mode you
      will have to do that manually.  For example, older
      versions allowed you to use

          0 bruce@broadcast.sony.com

      This version requires that you use:

          3,0 bruce@broadcast.sony.com


           As of version 8.7, some other syntaxes are
      available in test mode:

      .Dxvalue  defines macro x to have the indicated value.
                This is useful when debugging rules that use
                the $&x syntax.

      .Ccvalue  adds the indicated value to class c.

      =Sruleset dumps the contents of the indicated ruleset.

      -ddebug-spec
                is equivalent to the command-line flag.

      Version 8.9 introduced more features:

      ?         shows a help message.

      =M        display the known mailers.

      $m        print the value of macro m.

      $=c       print the contents of class c.

      /mx host  returns the MX records for `host'.

      /parse address
                parse address, returning the value of
                crackaddr, and the parsed address.

      /try mailer addr
                rewrite address into the form it will have










SMM:08-40          Sendmail Installation and Operation Guide


                when presented to the indicated mailer.

      /tryflags flags
                set flags used by parsing.  The flags can be
                `H' for Header or `E' for Envelope, and `S'
                for Sender or `R' for Recipient.  These can
                be combined, `HR' sets flags for header
                recipients.

      /canon hostname
                try to canonify hostname.

      /map mapname key
                look up `key' in the indicated `mapname'.

      /quit     quit address test mode.

   3.9.  Persistent Host Status Information

           When HostStatusDirectory is enabled, information
      about the status of hosts is maintained on disk and
      can thus be shared between different instantiations of
      sendmail.  The status of the last connection with each
      remote host may be viewed with the command:

          sendmail -bh

      This information may be flushed with the command:

          sendmail -bH

      Flushing the information prevents new sendmail
      processes from loading it, but does not prevent
      existing processes from using the status information
      that they already have.

4.  TUNING

        There are a number of configuration parameters you
   may want to change, depending on the requirements of your
   site.  Most of these are set using an option in the
   configuration file.  For example, the line "O
   Timeout.queuereturn=5d" sets option "Timeout.queuereturn"
   to the value "5d" (five days).

        Most of these options have appropriate defaults for
   most sites.  However, sites having very high mail loads
   may find they need to tune them as appropriate for their
   mail load.  In particular, sites experiencing a large
   number of small messages, many of which are delivered to
   many recipients, may find that they need to adjust the
   parameters dealing with queue priorities.











Sendmail Installation and Operation Guide          SMM:08-41


        All versions of sendmail prior to 8.7 had single
   character option names.  As of 8.7, options have long
   (multi-character names).  Although old short names are
   still accepted, most new options do not have short
   equivalents.

        This section only describes the options you are most
   likely to want to tweak; read section 5 for more details.

   4.1.  Timeouts

           All time intervals are set using a scaled syntax.
      For example, "10m" represents ten minutes, whereas
      "2h30m" represents two and a half hours.  The full set
      of scales is:

          s   seconds
          m   minutes
          h   hours
          d   days
          w   weeks


      4.1.1.  Queue interval

              The argument to the -q flag specifies how
         often a sub-daemon will run the queue.  This is
         typically set to between fifteen minutes and one
         hour.  If not set, or set to zero, the queue will
         not be run automatically.  RFC 1123 section 5.3.1.1
         recommends that this be at least 30 minutes.
         Should you need to terminate the queue jobs
         currently active then a SIGTERM to the parent of
         the process (or processes) will cleanly stop the
         jobs.

      4.1.2.  Read timeouts

              Timeouts all have option names
         "Timeout.suboption".  Most of these control SMTP
         operations.  The recognized suboptions, their
         default values, and the minimum values allowed by
         RFC 2821 section 4.5.3.2 (or RFC 1123 section
         5.3.2) are:

         connect   The time to wait for an SMTP connection
                   to open (the connect(2) system call) [0,
                   unspecified].  If zero, uses the kernel
                   default.  In no case can this option
                   extend the timeout longer than the kernel
                   provides, but it can shorten it.  This is
                   to get around kernels that provide an
                   absurdly long connection timeout (90










SMM:08-42          Sendmail Installation and Operation Guide


                   minutes in one case).

         iconnect  The same as connect, except it applies
                   only to the initial attempt to connect to
                   a host for a given message [0,
                   unspecified].  The concept is that this
                   should be very short (a few seconds);
                   hosts that are well connected and
                   responsive will thus be serviced
                   immediately.  Hosts that are slow will
                   not hold up other deliveries in the
                   initial delivery attempt.

         aconnect  [0, unspecified] The overall timeout
                   waiting for all connection for a single
                   delivery attempt to succeed.  If 0, no
                   overall limit is applied.  This can be
                   used to restrict the total amount of time
                   trying to connect to a long list of host
                   that could accept an e-mail for the
                   recipient.  This timeout does not apply
                   to FallbackMXhost, i.e., if the time is
                   exhausted, the FallbackMXhost is tried
                   next.

         initial   The wait for the initial 220 greeting
                   message [5m, 5m].

         helo      The wait for a reply from a HELO or EHLO
                   command [5m, unspecified].  This may
                   require a host name lookup, so five
                   minutes is probably a reasonable minimum.

         mail*     The wait for a reply from a MAIL command
                   [10m, 5m].

         rcpt*     The wait for a reply from a RCPT command
                   [1h, 5m].  This should be long because it
                   could be pointing at a list that takes a
                   long time to expand (see below).

         datainit* The wait for a reply from a DATA command
                   [5m, 2m].

         datablock*#
                   The wait for reading a data block (that
                   is, the body of the message).  [1h, 3m].
                   This should be long because it also
                   applies to programs piping input to
                   sendmail which have no guarantee of
                   promptness.












Sendmail Installation and Operation Guide          SMM:08-43


         datafinal*
                   The wait for a reply from the dot
                   terminating a message.  [1h, 10m].  If
                   this is shorter than the time actually
                   needed for the receiver to deliver the
                   message, duplicates will be generated.
                   This is discussed in RFC 1047.

         rset      The wait for a reply from a RSET command
                   [5m, unspecified].

         quit      The wait for a reply from a QUIT command
                   [2m, unspecified].

         misc      The wait for a reply from miscellaneous
                   (but short) commands such as NOOP (no-
                   operation) and VERB (go into verbose
                   mode).  [2m, unspecified].

         command*# In server SMTP, the time to wait for
                   another command.  [1h, 5m].

         ident#    The timeout waiting for a reply to an
                   IDENT query [5s[13], unspecified].

         lhlo      The wait for a reply to an LMTP LHLO
                   command [2m, unspecified].

         auth      The timeout for a reply in an SMTP AUTH
                   dialogue [10m, unspecified].

         starttls  The timeout for a reply to an SMTP
                   STARTTLS command and the TLS handshake
                   [1h, unspecified].

         fileopen# The timeout for opening .forward and
                   :include: files [60s, none].

         control#  The timeout for a complete control socket
                   transaction to complete [2m, none].

         hoststatus#
                   How long status information about a host
                   (e.g., host down) will be cached before
                   it is considered stale [30m,
                   unspecified].


____________________
   [13]On  some  systems  the  default  is  zero to turn the
protocol off entirely.












SMM:08-44          Sendmail Installation and Operation Guide


         resolver.retrans#
                   The resolver's retransmission time
                   interval (in seconds) [varies].  Sets
                   both Timeout.resolver.retrans.first and
                   Timeout.resolver.retrans.normal.

         resolver.retrans.first#
                   The resolver's retransmission time
                   interval (in seconds) for the first
                   attempt to deliver a message [varies].

         resolver.retrans.normal#
                   The resolver's retransmission time
                   interval (in seconds) for all resolver
                   lookups except the first delivery attempt
                   [varies].

         resolver.retry#
                   The number of times to retransmit a
                   resolver query.  Sets both
                   Timeout.resolver.retry.first and
                   Timeout.resolver.retry.normal [varies].

         resolver.retry.first#
                   The number of times to retransmit a
                   resolver query for the first attempt to
                   deliver a message [varies].

         resolver.retry.normal#
                   The number of times to retransmit a
                   resolver query for all resolver lookups
                    except the first delivery attempt
                   [varies].

         For compatibility with old configuration files, if
         no suboption is specified, all the timeouts marked
         with an asterick (*) are set to the indicated
         value.  All but those marked with a pound sign (#)
         apply to client SMTP.

              For example, the lines:

             O Timeout.command=25m
             O Timeout.datablock=3h

         sets the server SMTP command timeout to 25 minutes
         and the input data block timeout to three hours.

      4.1.3.  Message timeouts

              After sitting in the queue for a few days, an
         undeliverable message will time out.  This is to
         insure that at least the sender is aware of the










Sendmail Installation and Operation Guide          SMM:08-45


         inability to send a message.  The timeout is
         typically set to five days.  It is sometimes
         considered convenient to also send a warning
         message if the message is in the queue longer than
         a few hours (assuming you normally have good
         connectivity; if your messages normally took
         several hours to send you wouldn't want to do this
         because it wouldn't be an unusual event).  These
         timeouts are set using the Timeout.queuereturn and
         Timeout.queuewarn options in the configuration file
         (previously both were set using the T option).

              If the message is submitted using the NOTIFY
         SMTP extension, warning messages will only be sent
         if NOTIFY=DELAY is specified.  The queuereturn and
         queuewarn timeouts can be further qualified with a
         tag based on the Precedence: field in the message;
         they must be one of "urgent" (indicating a positive
         non-zero precedence), "normal" (indicating a zero
         precedence), or "non-urgent" (indicating negative
         precedences).  For example, setting
         "Timeout.queuewarn.urgent=1h" sets the warning
         timeout for urgent messages only to one hour.  The
         default if no precedence is indicated is to set the
         timeout for all precedences.  If the message has a
         normal (default) precedence and it is a delivery
         status notification (DSN), Timeout.queuereturn.dsn
         and Timeout.queuewarn.dsn can be used to give an
         alternative warn and return time for DSNs.  The
         value "now" can be used for -O Timeout.queuereturn
         to return entries immediately during a queue run,
         e.g., to bounce messages independent of their time
         in the queue.

              Since these options are global, and since you
         cannot know a priori how long another host outside
         your domain will be down, a five day timeout is
         recommended.  This allows a recipient to fix the
         problem even if it occurs at the beginning of a
         long weekend.  RFC 1123 section 5.3.1.1 says that
         this parameter should be ``at least 4-5 days''.

              The Timeout.queuewarn value can be piggybacked
         on the T option by indicating a time after which a
         warning message should be sent; the two timeouts
         are separated by a slash.  For example, the line

             OT5d/4h

         causes email to fail after five days, but a warning
         message will be sent after four hours.  This should
         be large enough that the message will have been
         tried several times.










SMM:08-46          Sendmail Installation and Operation Guide


   4.2.  Forking During Queue Runs

           By setting the ForkEachJob (Y) option, sendmail
      will fork before each individual message while running
      the queue.  This option was used with earlier releases
      to prevent sendmail from consuming large amounts of
      memory.  It should no longer be necessary with
      sendmail 8.12.  If the ForkEachJob option is not set,
      sendmail will keep track of hosts that are down during
      a queue run, which can improve performance
      dramatically.

           If the ForkEachJob option is set, sendmail cannot
      use connection caching.

   4.3.  Queue Priorities

           Every message is assigned a priority when it is
      first instantiated, consisting of the message size (in
      bytes) offset by the message class (which is
      determined from the Precedence: header) times the
      "work class factor" and the number of recipients times
      the "work recipient factor."  The priority is used to
      order the queue.  Higher numbers for the priority mean
      that the message will be processed later when running
      the queue.

           The message size is included so that large
      messages are penalized relative to small messages.
      The message class allows users to send "high priority"
      messages by including a "Precedence:" field in their
      message; the value of this field is looked up in the P
      lines of the configuration file.  Since the number of
      recipients affects the amount of load a message
      presents to the system, this is also included into the
      priority.

           The recipient and class factors can be set in the
      configuration file using the RecipientFactor (y) and
      ClassFactor (z) options respectively.  They default to
      30000 (for the recipient factor) and 1800 (for the
      class factor).  The initial priority is:

     pri=msgsize-(classxClassFactor)+(nrcptxRecipientFactor)

      (Remember, higher values for this parameter actually
      mean that the job will be treated with lower
      priority.)

           The priority of a job can also be adjusted each
      time it is processed (that is, each time an attempt is
      made to deliver it) using the "work time factor," set
      by the RetryFactor (Z) option.  This is added to the










Sendmail Installation and Operation Guide          SMM:08-47


      priority, so it normally decreases the precedence of
      the job, on the grounds that jobs that have failed
      many times will tend to fail again in the future.  The
      RetryFactor option defaults to 90000.

   4.4.  Load Limiting

           Sendmail can be asked to queue (but not deliver)
      mail if the system load average gets too high using
      the QueueLA (x) option.  When the load average exceeds
      the value of the QueueLA option, the delivery mode is
      set to q (queue only) if the QueueFactor (q) option
      divided by the difference in the current load average
      and the QueueLA option plus one is less than the
      priority of the message -- that is, the message is
      queued iff:

                        pri>LQueueFactor_

      The QueueFactor option defaults to 600000, so each
      point of load average is worth 600000 priority points
      (as described above).

           For drastic cases, the RefuseLA (X) option
      defines a load average at which sendmail will refuse
      to accept network connections.  Locally generated
      mail, i.e., mail which is not submitted via SMTP
      (including incoming UUCP mail), is still accepted.
      Notice that the MSP submits mail to the MTA via SMTP,
      and hence mail will be queued in the client queue in
      such a case.  Therefore it is necessary to run the
      client mail queue periodically.

   4.5.  Resource Limits

           Sendmail has several parameters to control
      resource usage.  Besides those mentioned in the
      previous section, there are at least
      MaxDaemonChildren, ConnectionRateThrottle,
      MaxQueueChildren, and MaxRunnersPerQueue.  The latter
      two limit the number of sendmail processes that
      operate on the queue.  These are discussed in the
      section ``Queue Group Declaration''.  The former two
      can be used to limit the number of incoming
      connections.  Their appropriate values depend on the
      host operating system and the hardware, e.g., amount
      of memory.  In many situations it might be useful to
      set limits to prevent to have too many sendmail
      processes, however, these limits can be abused to
      mount a denial of service attack.  For example, if
      MaxDaemonChildren=10 then an attacker needs to open
      only 10 SMTP sessions to the server, leave them idle
      for most of the time, and no more connections will be










SMM:08-48          Sendmail Installation and Operation Guide


      accepted.  If this option is set then the timeouts
      used in a SMTP session should be lowered from their
      default values to their minimum values as specified in
      RFC 2821 and listed in section 4.1.2.

   4.6.  Measures against Denial of Service Attacks

           Sendmail has some built-in measures against
      simple denial of service (DoS) attacks.  The SMTP
      server by default slows down if too many bad commands
      are issued or if some commands are repeated too often
      within a session.  Details can be found in the source
      file sendmail/srvrsmtp.c by looking for the macro
      definitions of MAXBADCOMMANDS, MAXNOOPCOMMANDS,
      MAXHELOCOMMANDS, MAXVRFYCOMMANDS, and MAXETRNCOMMANDS.
      If an SMTP command is issued more often than the
      corresponding MAXcmdCOMMANDS value, then the response
      is delayed exponentially, starting with a sleep time
      of one second, up to a maximum of four minutes (as
      defined by MAXTIMEOUT).  If the option
      MaxDaemonChildren is set to a value greater than zero,
      then this could make a DoS attack even worse since it
      keeps a connection open longer than necessary.
      Therefore a connection is terminated with a 421 SMTP
      reply code if the number of commands exceeds the limit
      by a factor of two and MAXBADCOMMANDS is set to a
      value greater than zero (the default is 25).

   4.7.  Delivery Mode

           There are a number of delivery modes that
      sendmail can operate in, set by the DeliveryMode (d)
      configuration option.  These modes specify how quickly
      mail will be delivered.  Legal modes are:

          i   deliver interactively (synchronously)
          b   deliver in background (asynchronously)
          q   queue only (don't deliver)
          d   defer delivery attempts (don't deliver)

      There are tradeoffs.  Mode "i" gives the sender the
      quickest feedback, but may slow down some mailers and
      is hardly ever necessary.  Mode "b" delivers promptly
      but can cause large numbers of processes if you have a
      mailer that takes a long time to deliver a message.
      Mode "q" minimizes the load on your machine, but means
      that delivery may be delayed for up to the queue
      interval.  Mode "d" is identical to mode "q" except
      that it also prevents lookups in maps including the -D
      flag from working during the initial queue phase; it
      is intended for ``dial on demand'' sites where DNS
      lookups might cost real money.  Some simple error
      messages (e.g., host unknown during the SMTP protocol)










Sendmail Installation and Operation Guide          SMM:08-49


      will be delayed using this mode.  Mode "b" is the
      usual default.

           If you run in mode "q" (queue only), "d" (defer),
      or "b" (deliver in background) sendmail will not
      expand aliases and follow .forward files upon initial
      receipt of the mail.  This speeds up the response to
      RCPT commands.  Mode "i" should not be used by the
      SMTP server.

   4.8.  Log Level

           The level of logging can be set for sendmail.
      The default using a standard configuration is level 9.
      The levels are approximately as follows (some log
      types are using different level depending on various
      factors):

      0    Minimal logging.

      1    Serious system failures and potential security
           problems.

      2    Lost communications (network problems) and
           protocol failures.

      3    Other serious failures, malformed addresses,
           transient forward/include errors, connection
           timeouts.

      4    Minor failures, out of date alias databases,
           connection rejections via check_ rulesets.

      5    Message collection statistics.

      6    Creation of error messages, VRFY and EXPN
           commands.

      7    Delivery failures (host or user unknown, etc.).

      8    Successful deliveries and alias database
           rebuilds.

      9    Messages being deferred (due to a host being
           down, etc.).

      10   Database expansion (alias, forward, and userdb
           lookups) and authentication information.

      11   NIS errors and end of job processing.

      12   Logs all SMTP connections.











SMM:08-50          Sendmail Installation and Operation Guide


      13   Log bad user shells, files with improper
           permissions, and other questionable situations.

      14   Logs refused connections.

      15   Log all incoming SMTP commands.

      20   Logs attempts to run locked queue files.  These
           are not errors, but can be useful to note if your
           queue appears to be clogged.

      30   Lost locks (only if using lockf instead of
           flock).

      Additionally, values above 64 are reserved for
      extremely verbose debugging output.  No normal site
      would ever set these.

   4.9.  File Modes

           The modes used for files depend on what
      functionality you want and the level of security you
      require.  In many cases sendmail does careful checking
      of the modes of files and directories to avoid
      accidental compromise; if you want to make it possible
      to have group-writable support files you may need to
      use the DontBlameSendmail option to turn off some of
      these checks.

      4.9.1.  To suid or not to suid?

              Sendmail is no longer installed set-user-ID to
         root.  sendmail/SECURITY explains how to configure
         and install sendmail without set-user-ID to root
         but set-group-ID which is the default configuration
         starting with 8.12.

              The daemon usually runs as root, unless other
         measures are taken.  At the point where sendmail is
         about to exec(2) a mailer, it checks to see if the
         userid is zero (root); if so, it resets the userid
         and groupid to a default (set by the U= equate in
         the mailer line; if that is not set, the
         DefaultUser option is used).  This can be
         overridden by setting the S flag to the mailer for
         mailers that are trusted and must be called as
         root.  However, this will cause mail processing to
         be accounted (using sa(8)) to root rather than to
         the user sending the mail.

              A middle ground is to set the RunAsUser
         option.  This causes sendmail to become the
         indicated user as soon as it has done the startup










Sendmail Installation and Operation Guide          SMM:08-51


         that requires root privileges (primarily, opening
         the SMTP socket).  If you use RunAsUser, the queue
         directory (normally /var/spool/mqueue) should be
         owned by that user, and all files and databases
         (including user .forward files, alias files,
         :include: files, and external databases) must be
         readable by that user.  Also, since sendmail will
         not be able to change its uid, delivery to programs
         or files will be marked as unsafe, e.g.,
         undeliverable, in .forward, aliases, and :include:
         files.  Administrators can override this by setting
         the DontBlameSendmail option to the setting
         NonRootSafeAddr.  RunAsUser is probably best suited
         for firewall configurations that don't have regular
         user logins.  If the option is used on a system
         which performs local delivery, then the local
         delivery agent must have the proper permissions
         (i.e., usually set-user-ID root) since it will be
         invoked by the RunAsUser, not by root.

      4.9.2.  Turning off security checks

              Sendmail is very particular about the modes of
         files that it reads or writes.  For example, by
         default it will refuse to read most files that are
         group writable on the grounds that they might have
         been tampered with by someone other than the owner;
         it will even refuse to read files in group writable
         directories.  Also, sendmail will refuse to create
         a new aliases database in an unsafe directory.  You
         can get around this by manually creating the
         database file as a trusted user ahead of time and
         then rebuilding the aliases database with
         newaliases.

              If you are quite sure that your configuration
         is safe and you want sendmail to avoid these
         security checks, you can turn off certain checks
         using the DontBlameSendmail option.  This option
         takes one or more names that disable checks.  In
         the descriptions that follow, "unsafe directory"
         means a directory that is writable by anyone other
         than the owner.  The values are:

         Safe No special handling.

         AssumeSafeChown
              Assume that the chown system call is
              restricted to root.  Since some versions of
              UNIX permit regular users to give away their
              files to other users on some filesystems,
              sendmail often cannot assume that a given file
              was created by the owner, particularly when it










SMM:08-52          Sendmail Installation and Operation Guide


              is in a writable directory.  You can set this
              flag if you know that file giveaway is
              restricted on your system.

         ClassFileInUnsafeDirPath
              When reading class files (using the F line in
              the configuration file), allow files that are
              in unsafe directories.

         DontWarnForwardFileInUnsafeDirPath
              Prevent logging of unsafe directory path
              warnings for non-existent forward files.

         ErrorHeaderInUnsafeDirPath
              Allow the file named in the ErrorHeader option
              to be in an unsafe directory.

         FileDeliveryToHardLink
              Allow delivery to files that are hard links.

         FileDeliveryToSymLink
              Allow delivery to files that are symbolic
              links.

         ForwardFileInGroupWritableDirPath
              Allow .forward files in group writable
              directories.

         ForwardFileInUnsafeDirPath
              Allow .forward files in unsafe directories.

         ForwardFileInUnsafeDirPathSafe
              Allow a .forward file that is in an unsafe
              directory to include references to program and
              files.

         GroupReadableKeyFile
              Accept a group-readable key file for STARTTLS.

         GroupReadableSASLDBFile
              Accept a group-readable Cyrus SASL password
              file.

         GroupReadableDefaultAuthInfoFile
              Accept a group-readable DefaultAuthInfo file
              for SASL.

         GroupWritableAliasFile
              Allow group-writable alias files.

         GroupWritableDirPathSafe
              Change the definition of "unsafe directory" to
              consider group-writable directories to be










Sendmail Installation and Operation Guide          SMM:08-53


              safe.  World-writable directories are always
              unsafe.

         GroupWritableForwardFile
              Allow group writable .forward files.

         GroupWritableForwardFileSafe
              Accept group-writable .forward files as safe
              for program and file delivery.

         GroupWritableIncludeFile
              Allow group writable :include: files.

         GroupWritableIncludeFileSafe
              Accept group-writable :include: files as safe
              for program and file delivery.

         GroupWritableSASLDBFile
              Accept a group-writable Cyrus SASL password
              file.

         HelpFileInUnsafeDirPath
              Allow the file named in the HelpFile option to
              be in an unsafe directory.

         IncludeFileInGroupWritableDirPath
              Allow :include: files in group writable
              directories.

         IncludeFileInUnsafeDirPath
              Allow :include: files in unsafe directories.

         IncludeFileInUnsafeDirPathSafe
              Allow a :include: file that is in an unsafe
              directory to include references to program and
              files.

         InsufficientEntropy
              Try to use STARTTLS even if the PRNG for
              OpenSSL is not properly seeded despite the
              security problems.

         LinkedAliasFileInWritableDir
              Allow an alias file that is a link in a
              writable directory.

         LinkedClassFileInWritableDir
              Allow class files that are links in writable
              directories.

         LinkedForwardFileInWritableDir
              Allow .forward files that are links in
              writable directories.










SMM:08-54          Sendmail Installation and Operation Guide


         LinkedIncludeFileInWritableDir
              Allow :include: files that are links in
              writable directories.

         LinkedMapInWritableDir
              Allow map files that are links in writable
              directories.  This includes alias database
              files.

         LinkedServiceSwitchFileInWritableDir
              Allow the service switch file to be a link
              even if the directory is writable.

         MapInUnsafeDirPath
              Allow maps (e.g., hash, btree, and dbm files)
              in unsafe directories.  This includes alias
              database files.

         NonRootSafeAddr
              Do not mark file and program deliveries as
              unsafe if sendmail is not running with root
              privileges.

         RunProgramInUnsafeDirPath
              Run programs that are in writable directories
              without logging a warning.

         RunWritableProgram
              Run programs that are group- or world-writable
              without logging a warning.

         TrustStickyBit
              Allow group or world writable directories if
              the sticky bit is set on the directory.  Do
              not set this on systems which do not honor the
              sticky bit on directories.

         WorldWritableAliasFile
              Accept world-writable alias files.

         WorldWritableForwardfile
              Allow world writable .forward files.

         WorldWritableIncludefile
              Allow world writable :include: files.

         WriteMapToHardLink
              Allow writes to maps that are hard links.

         WriteMapToSymLink
              Allow writes to maps that are symbolic links.












Sendmail Installation and Operation Guide          SMM:08-55


         WriteStatsToHardLink
              Allow the status file to be a hard link.

         WriteStatsToSymLink
              Allow the status file to be a symbolic link.

   4.10.  Connection Caching

           When processing the queue, sendmail will try to
      keep the last few open connections open to avoid
      startup and shutdown costs.  This only applies to IPC
      and LPC connections.

           When trying to open a connection the cache is
      first searched.  If an open connection is found, it is
      probed to see if it is still active by sending a RSET
      command.  It is not an error if this fails; instead,
      the connection is closed and reopened.

           Two parameters control the connection cache.  The
      ConnectionCacheSize (k) option defines the number of
      simultaneous open connections that will be permitted.
      If it is set to zero, connections will be closed as
      quickly as possible.  The default is one.  This should
      be set as appropriate for your system size; it will
      limit the amount of system resources that sendmail
      will use during queue runs.  Never set this higher
      than 4.

           The ConnectionCacheTimeout (K) option specifies
      the maximum time that any cached connection will be
      permitted to idle.  When the idle time exceeds this
      value the connection is closed.  This number should be
      small (under ten minutes) to prevent you from grabbing
      too many resources from other hosts.  The default is
      five minutes.

   4.11.  Name Server Access

           Control of host address lookups is set by the
      hosts service entry in your service switch file.  If
      you are on a system that has built-in service switch
      support (e.g., Ultrix, Solaris, or DEC OSF/1) then
      your system is probably configured properly already.
      Otherwise, sendmail will consult the file
      /etc/mail/service.switch, which should be created.
      Sendmail only uses two entries: hosts and aliases,
      although system routines may use other services
      (notably the passwd service for user name lookups by
      getpwname).

           However, some systems (such as SunOS 4.X) will do
      DNS lookups regardless of the setting of the service










SMM:08-56          Sendmail Installation and Operation Guide


      switch entry.  In particular, the system routine
      gethostbyname(3) is used to look up host names, and
      many vendor versions try some combination of DNS, NIS,
      and file lookup in /etc/hosts without consulting a
      service switch.  Sendmail makes no attempt to work
      around this problem, and the DNS lookup will be done
      anyway.  If you do not have a nameserver configured at
      all, such as at a UUCP-only site, sendmail will get a
      "connection refused" message when it tries to connect
      to the name server.  If the hosts switch entry has the
      service "dns" listed somewhere in the list, sendmail
      will interpret this to mean a temporary failure and
      will queue the mail for later processing; otherwise,
      it ignores the name server data.

           The same technique is used to decide whether to
      do MX lookups.  If you want MX support, you must have
      "dns" listed as a service in the hosts switch entry.

           The ResolverOptions (I) option allows you to
      tweak name server options.  The command line takes a
      series of flags as documented in resolver(3) (with the
      leading "RES_" deleted).  Each can be preceded by an
      optional `+' or `-'.  For example, the line

          O ResolverOptions=+AAONLY -DNSRCH

      turns on the AAONLY (accept authoritative answers
      only) and turns off the DNSRCH (search the domain
      path) options.  Most resolver libraries default
      DNSRCH, DEFNAMES, and RECURSE flags on and all others
      off.  If NETINET6 is enabled, most libraries default
      to USE_INET6 as well.  You can also include
      "HasWildcardMX" to specify that there is a wildcard MX
      record matching your domain; this turns off MX
      matching when canonifying names, which can lead to
      inappropriate canonifications.  Use
      "WorkAroundBrokenAAAA" when faced with a broken
      nameserver that returns SERVFAIL (a temporary failure)
      on T_AAAA (IPv6) lookups during hostname
      canonification.  Notice: it might be necessary to
      apply the same (or similar) options to submit.cf too.

           Version level 1 configurations (see the section
      about ``Configuration Version Level'') turn DNSRCH and
      DEFNAMES off when doing delivery lookups, but leave
      them on everywhere else.  Version 8 of sendmail
      ignores them when doing canonification lookups (that
      is, when using $[ ... $]), and always does the search.
      If you don't want to do automatic name extension,
      don't call $[ ... $].












Sendmail Installation and Operation Guide          SMM:08-57


           The search rules for $[ ... $] are somewhat
      different than usual.  If the name being looked up has
      at least one dot, it always tries the unmodified name
      first.  If that fails, it tries the reduced search
      path, and lastly tries the unmodified name (but only
      for names without a dot, since names with a dot have
      already been tried).  This allows names such as
      ``utc.CS'' to match the site in Czechoslovakia rather
      than the site in your local Computer Science
      department.  It also prefers A and CNAME records over
      MX records -- that is, if it finds an MX record it
      makes note of it, but keeps looking.  This way, if you
      have a wildcard MX record matching your domain, it
      will not assume that all names match.

           To completely turn off all name server access on
      systems without service switch support (such as SunOS
      4.X) you will have to recompile with -DNAMED_BIND=0
      and remove -lresolv from the list of libraries to be
      searched when linking.

   4.12.  Moving the Per-User Forward Files

           Some sites mount each user's home directory from
      a local disk on their workstation, so that local
      access is fast.  However, the result is that .forward
      file lookups from a central mail server are slow.  In
      some cases, mail can even be delivered on machines
      inappropriately because of a file server being down.
      The performance can be especially bad if you run the
      automounter.

           The ForwardPath (J) option allows you to set a
      path of forward files.  For example, the config file
      line

          O ForwardPath=/var/forward/$u:$z/.forward.$w

      would first look for a file with the same name as the
      user's login in /var/forward; if that is not found (or
      is inaccessible) the file ``.forward.machinename'' in
      the user's home directory is searched.  A truly
      perverse site could also search by sender by using $r,
      $s, or $f.

           If you create a directory such as /var/forward,
      it should be mode 1777 (that is, the sticky bit should
      be set).  Users should create the files mode 0644.
      Note that you must use the ForwardFileInUnsafeDirPath
      and ForwardFileInUnsafeDirPathSafe flags with the
      DontBlameSendmail option to allow forward files in a
      world writable directory.  This might also be used as
      a denial of service attack (users could create forward










SMM:08-58          Sendmail Installation and Operation Guide


      files for other users); a better approach might be to
      create /var/forward mode 0755 and create empty files
      for each user, owned by that user, mode 0644.  If you
      do this, you don't have to set the DontBlameSendmail
      options indicated above.

   4.13.  Free Space

           On systems that have one of the system calls in
      the statfs(2) family (including statvfs and ustat),
      you can specify a minimum number of free blocks on the
      queue filesystem using the MinFreeBlocks (b) option.
      If there are fewer than the indicated number of blocks
      free on the filesystem on which the queue is mounted
      the SMTP server will reject mail with the 452 error
      code.  This invites the SMTP client to try again
      later.

           Beware of setting this option too high; it can
      cause rejection of email when that mail would be
      processed without difficulty.

   4.14.  Maximum Message Size

           To avoid overflowing your system with a large
      message, the MaxMessageSize option can be set to set
      an absolute limit on the size of any one message.
      This will be advertised in the ESMTP dialogue and
      checked during message collection.

   4.15.  Privacy Flags

           The PrivacyOptions (p) option allows you to set
      certain ``privacy'' flags.  Actually, many of them
      don't give you any extra privacy, rather just
      insisting that client SMTP servers use the HELO
      command before using certain commands or adding extra
      headers to indicate possible spoof attempts.

           The option takes a series of flag names; the
      final privacy is the inclusive or of those flags.  For
      example:

          O PrivacyOptions=needmailhelo, noexpn

      insists that the HELO or EHLO command be used before a
      MAIL command is accepted and disables the EXPN
      command.

           The flags are detailed in section 5.6.













Sendmail Installation and Operation Guide          SMM:08-59


   4.16.  Send to Me Too

           Beginning with version 8.10, sendmail includes by
      default the (envelope) sender in any list expansions.
      For example, if "matt" sends to a list that contains
      "matt" as one of the members he will get a copy of the
      message.  If the MeToo option is set to FALSE (in the
      configuration file or via the command line), this
      behavior is changed, i.e., the (envelope) sender is
      excluded in list expansions.

5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE

        This section describes the configuration file in
   detail.

        There is one point that should be made clear
   immediately: the syntax of the configuration file is
   designed to be reasonably easy to parse, since this is
   done every time sendmail starts up, rather than easy for
   a human to read or write.  The configuration file should
   be generated via the method described in cf/README, it
   should not be edited directly unless someone is familiar
   with the internals of the syntax described here and it is
   not possible to achieve the desired result via the
   default method.

        The configuration file is organized as a series of
   lines, each of which begins with a single character
   defining the semantics for the rest of the line.  Lines
   beginning with a space or a tab are continuation lines
   (although the semantics are not well defined in many
   places).  Blank lines and lines beginning with a sharp
   symbol (`#') are comments.

   5.1.  R and S -- Rewriting Rules

           The core of address parsing are the rewriting
      rules.  These are an ordered production system.
      Sendmail scans through the set of rewriting rules
      looking for a match on the left hand side (LHS) of the
      rule.  When a rule matches, the address is replaced by
      the right hand side (RHS) of the rule.

           There are several sets of rewriting rules.  Some
      of the rewriting sets are used internally and must
      have specific semantics.  Other rewriting sets do not
      have specifically assigned semantics, and may be
      referenced by the mailer definitions or by other
      rewriting sets.

           The syntax of these two commands are:











SMM:08-60          Sendmail Installation and Operation Guide


          Sn

      Sets the current ruleset being collected to n.  If you
      begin a ruleset more than once it appends to the old
      definition.

          Rlhs rhs comments

      The fields must be separated by at least one tab
      character; there may be embedded spaces in the fields.
      The lhs is a pattern that is applied to the input.  If
      it matches, the input is rewritten to the rhs.  The
      comments are ignored.

           Macro expansions of the form $x are performed
      when the configuration file is read.  A literal $ can
      be included using $$.  Expansions of the form $&x are
      performed at run time using a somewhat less general
      algorithm.  This is intended only for referencing
      internally defined macros such as $h that are changed
      at runtime.

      5.1.1.  The left hand side

              The left hand side of rewriting rules contains
         a pattern.  Normal words are simply matched
         directly.  Metasyntax is introduced using a dollar
         sign.  The metasymbols are:

             $*   Match zero or more tokens
             $+   Match one or more tokens
             $-   Match exactly one token
             $=x  Match any phrase in class x
             $~x  Match any word not in class x

         If any of these match, they are assigned to the
         symbol $n for replacement on the right hand side,
         where n is the index in the LHS.  For example, if
         the LHS:

             $-:$+

         is applied to the input:

             UCBARPA:eric

         the rule will match, and the values passed to the
         RHS will be:

             $1  UCBARPA
             $2  eric












Sendmail Installation and Operation Guide          SMM:08-61


              Additionally, the LHS can include $@ to match
         zero tokens.  This is not bound to a $n on the RHS,
         and is normally only used when it stands alone in
         order to match the null input.

      5.1.2.  The right hand side

              When the left hand side of a rewriting rule
         matches, the input is deleted and replaced by the
         right hand side.  Tokens are copied directly from
         the RHS unless they begin with a dollar sign.
         Metasymbols are:

             $n         Substitute indefinite token n from LHS
             $[name$]   Canonicalize name
             $(map key $@arguments $:default $)
                        Generalized keyed mapping function
             $>n        "Call" ruleset n
             $#mailer   Resolve to mailer
             $@host     Specify host
             $:user     Specify user


              The $n syntax substitutes the corresponding
         value from a $+, $-, $*, $=, or $~ match on the
         LHS.  It may be used anywhere.

              A host name enclosed between $[ and $] is
         looked up in the host database(s) and replaced by
         the canonical name[14].  For example, "$[ftp$]"
         might become "ftp.CS.Berkeley.EDU" and
         "$[[128.32.130.2]$]" would become
         "vangogh.CS.Berkeley.EDU."  Sendmail recognizes its
         numeric IP address without calling the name server
         and replaces it with its canonical name.

              The $( ...  $) syntax is a more general form
         of lookup; it uses a named map instead of an
         implicit map.  If no lookup is found, the indicated
         default is inserted; if no default is specified and
         no lookup matches, the value is left unchanged.
         The arguments are passed to the map for possible
         use.

              The $>n syntax causes the remainder of the
         line to be substituted as usual and then passed as
         the argument to ruleset n.  The final value of
         ruleset n then becomes the substitution for this
____________________
   [14]This is  actually  completely  equivalent  to  $(host
hostname$).  In particular, a $: default can be used.












SMM:08-62          Sendmail Installation and Operation Guide


         rule.  The $> syntax expands everything after the
         ruleset name to the end of the replacement string
         and then passes that as the initial input to the
         ruleset.  Recursive calls are allowed.  For
         example,

             $>0 $>3 $1

         expands $1, passes that to ruleset 3, and then
         passes the result of ruleset 3 to ruleset 0.

              The $# syntax should only be used in ruleset
         zero, a subroutine of ruleset zero, or rulesets
         that return decisions (e.g., check_rcpt).  It
         causes evaluation of the ruleset to terminate
         immediately, and signals to sendmail that the
         address has completely resolved.  The complete
         syntax for ruleset 0 is:

             $#mailer $@host $:user

         This specifies the {mailer, host, user} 3-tuple
         (triple) necessary to direct the mailer.  Note: the
         third element ( user ) is often also called address
         part.  If the mailer is local the host part may be
         omitted[15].  The mailer must be a single word, but
         the host and user may be multi-part.  If the mailer
         is the built-in IPC mailer, the host may be a colon
         (or comma) separated list of hosts.  Each is
         separately MX expanded and the results are
         concatenated to make (essentially) one long MX
         list.  Hosts separated by a comma have the same MX
         preference, and for each colon separated host the
         MX preference is increased.  The user is later
         rewritten by the mailer-specific envelope rewriting
         set and assigned to the $u macro.  As a special
         case, if the mailer specified has the F=@ flag
         specified and the first character of the $: value
         is "@", the "@" is stripped off, and a flag is set
         in the address descriptor that causes sendmail to
         not do ruleset 5 processing.

              Normally, a rule that matches is retried, that
         is, the rule loops until it fails.  A RHS may also
         be preceded by a $@ or a $: to change this
         behavior.  A $@ prefix causes the ruleset to return
____________________
   [15]You  may  want  to  use  it  for  special  "per user"
extensions.  For example, in the address  "jgm+foo@CMU.EDU";
the  "+foo" part is not part of the user name, and is passed
to the local mailer for local use.












Sendmail Installation and Operation Guide          SMM:08-63


         with the remainder of the RHS as the value.  A $:
         prefix causes the rule to terminate immediately,
         but the ruleset to continue; this can be used to
         avoid continued application of a rule.  The prefix
         is stripped before continuing.

              The $@ and $: prefixes may precede a $> spec;
         for example:

             R$+     $: $>7 $1

         matches anything, passes that to ruleset seven, and
         continues; the $: is necessary to avoid an infinite
         loop.

              Substitution occurs in the order described,
         that is, parameters from the LHS are substituted,
         hostnames are canonicalized, "subroutines" are
         called, and finally $#, $@, and $: are processed.

      5.1.3.  Semantics of rewriting rule sets

              There are six rewriting sets that have
         specific semantics.  Five of these are related as
         depicted by figure 1.

              Ruleset three should turn the address into
         "canonical form."  This form should have the basic
         syntax:


____________________________________________________________

                    +---+
                 -->| 0 |-->resolved address
                /   +---+
               /            +---+   +---+
              /        ---->| 1 |-->| S |--
       +---+ / +---+  /     +---+   +---+  \    +---+
addr-->| 3 |-->| D |--                      --->| 4 |-->msg
       +---+   +---+  \     +---+   +---+  /    +---+
                        --->| 2 |-->| R |--
                            +---+   +---+

            Figure 1 -- Rewriting set semantics
          D -- sender domain addition
          S -- mailer-specific sender rewriting
          R -- mailer-specific recipient rewriting
____________________________________________________________














SMM:08-64          Sendmail Installation and Operation Guide


             local-part@host-domain-spec

         Ruleset three is applied by sendmail before doing
         anything with any address.

              If no "@" sign is specified, then the host-
         domain-spec may be appended (box "D" in Figure 1)
         from the sender address (if the C flag is set in
         the mailer definition corresponding to the sending
         mailer).

              Ruleset zero is applied after ruleset three to
         addresses that are going to actually specify
         recipients.  It must resolve to a {mailer, host,
         address} triple.  The mailer must be defined in the
         mailer definitions from the configuration file.
         The host is defined into the $h macro for use in
         the argv expansion of the specified mailer.
         Notice: since the envelope sender address will be
         used if a delivery status notification must be
         send, i.e., it may specify a recipient, it is also
         run through ruleset zero.  If ruleset zero returns
         a temporary error 4xy then delivery is deferred.
         This can be used to temporarily disable delivery,
         e.g., based on the time of the day or other varying
         parameters.  It should not be used to quarantine e-
         mails.

              Rulesets one and two are applied to all sender
         and recipient addresses respectively.  They are
         applied before any specification in the mailer
         definition.  They must never resolve.

              Ruleset four is applied to all addresses in
         the message.  It is typically used to translate
         internal to external form.

              In addition, ruleset 5 is applied to all local
         addresses (specifically, those that resolve to a
         mailer with the `F=5' flag set) that do not have
         aliases.  This allows a last minute hook for local
         names.

      5.1.4.  Ruleset hooks

              A few extra rulesets are defined as "hooks"
         that can be defined to get special features.  They
         are all named rulesets.  The "check_*" forms all
         give accept/reject status; falling off the end or
         returning normally is an accept, and resolving to
         $#error is a reject or quarantine.  Quarantining is
         chosen by specifying quarantine in the second part
         of the mailer triplet:










Sendmail Installation and Operation Guide          SMM:08-65


             $#error $@ quarantine $: Reason for quarantine

         Many of these can also resolve to the special
         mailer name $#discard; this accepts the message as
         though it were successful but then discards it
         without delivery.  Note, this mailer cannot be
         chosen as a mailer in ruleset 0.  Note also that
         all "check_*" rulesets have to deal with temporary
         failures, especially for map lookups, themselves,
         i.e., they should return a temporary error code or
         at least they should make a proper decision in
         those cases.

         5.1.4.1.  check_relay

                 The check_relay ruleset is called after a
            connection is accepted by the daemon.  It is not
            called when sendmail is started using the -bs
            option.  It is passed

                client.host.name $| client.host.address

            where $| is a metacharacter separating the two
            parts.  This ruleset can reject connections from
            various locations.  Note that it only checks the
            connecting SMTP client IP address and hostname.
            It does not check for third party message
            relaying.  The check_rcpt ruleset discussed
            below usually does third party message relay
            checking.

         5.1.4.2.  check_mail

                 The check_mail ruleset is passed the user
            name parameter of the SMTP MAIL command.  It can
            accept or reject the address.

         5.1.4.3.  check_rcpt

                 The check_rcpt ruleset is passed the user
            name parameter of the SMTP RCPT command.  It can
            accept or reject the address.

         5.1.4.4.  check_data

                 The check_data ruleset is called after the
            SMTP DATA command, its parameter is the number
            of recipients.  It can accept or reject the
            command.














SMM:08-66          Sendmail Installation and Operation Guide


         5.1.4.5.  check_compat

                 The check_compat ruleset is passed

                sender-address $| recipient-address

            where $| is a metacharacter separating the
            addresses.  It can accept or reject mail
            transfer between these two addresses much like
            the checkcompat() function.  Note: while other
            check_* rulesets are invoked during the SMTP
            mail receiption stage (i.e., in the SMTP
            server), check_compat is invoked during the mail
            delivery stage.

         5.1.4.6.  check_eoh

                 The check_eoh ruleset is passed

                number-of-headers $| size-of-headers

            where $| is a metacharacter separating the
            numbers.  These numbers can be used for size
            comparisons with the arith map.  The ruleset is
            triggered after all of the headers have been
            read.  It can be used to correlate information
            gathered from those headers using the macro
            storage map.  One possible use is to check for a
            missing header.  For example:

                Kstorage macro
                HMessage-Id: $>CheckMessageId

                SCheckMessageId
                # Record the presence of the header
                R$*            $: $(storage {MessageIdCheck} $@ OK $) $1
                R< $+ @ $+ >   $@ OK
                R$*            $#error $: 553 Header Error

                Scheck_eoh
                # Check the macro
                R$*            $: < $&{MessageIdCheck} >
                # Clear the macro for the next message
                R$*            $: $(storage {MessageIdCheck} $) $1
                # Has a Message-Id: header
                R< $+ >        $@ OK
                # Allow missing Message-Id: from local mail
                R$*            $: < $&{client_name} >
                R< >           $@ OK
                R< $=w >       $@ OK
                # Otherwise, reject the mail
                R$*            $#error $: 553 Header Error











Sendmail Installation and Operation Guide          SMM:08-67


            Keep in mind the Message-Id: header is not a
            required header and is not a guaranteed spam
            indicator.  This ruleset is an example and
            should probably not be used in production.

         5.1.4.7.  check_eom

                 The check_eom ruleset is called after the
            end of a message, its parameter is the message
            size.  It can accept or reject the message.

         5.1.4.8.  check_etrn

                 The check_etrn ruleset is passed the
            parameter of the SMTP ETRN command.  It can
            accept or reject the command.

         5.1.4.9.  check_expn

                 The check_expn ruleset is passed the user
            name parameter of the SMTP EXPN command.  It can
            accept or reject the address.

         5.1.4.10.  check_vrfy

                 The check_vrfy ruleset is passed the user
            name parameter of the SMTP VRFY command.  It can
            accept or reject the command.

         5.1.4.11.  trust_auth

                 The trust_auth ruleset is passed the AUTH=
            parameter of the SMTP MAIL command.  It is used
            to determine whether this value should be
            trusted. In order to make this decision, the
            ruleset may make use of the various ${auth_*}
            macros.  If the ruleset does resolve to the
            "error" mailer the AUTH= parameter is not
            trusted and hence not passed on to the next
            relay.

         5.1.4.12.  tls_client

                 The tls_client ruleset is called when
            sendmail acts as server, after a STARTTLS
            command has been issued, and from check_mail.
            The parameter is the value of ${verify} and
            STARTTLS or MAIL, respectively.  If the ruleset
            does resolve to the "error" mailer, the
            appropriate error code is returned to the
            client.












SMM:08-68          Sendmail Installation and Operation Guide


         5.1.4.13.  tls_server

                 The tls_server ruleset is called when
            sendmail acts as client after a STARTTLS command
            (should) have been issued.  The parameter is the
            value of ${verify}.  If the ruleset does resolve
            to the "error" mailer, the connection is aborted
            (treated as non-deliverable with a permanent or
            temporary error).

         5.1.4.14.  tls_rcpt

                 The tls_rcpt ruleset is called each time
            before a RCPT TO command is sent.  The parameter
            is the current recipient.  If the ruleset does
            resolve to the "error" mailer, the RCPT TO
            command is suppressed (treated as non-
            deliverable with a permanent or temporary
            error).  This ruleset allows to require
            encryption or verification of the recipient's
            MTA even if the mail is somehow redirected to
            another host.  For example, sending mail to
            luke@endmail.org may get redirected to a host
            named death.star and hence the tls_server
            ruleset won't apply.  By introducing per
            recipient restrictions such attacks (e.g., via
            DNS spoofing) can be made impossible.  See
            cf/README how this ruleset can be used.

         5.1.4.15.  srv_features

                 The srv_features ruleset is called with the
            connecting client's host name when a client
            connects to sendmail.  This ruleset should
            return $# followed by a list of options (single
            characters delimited by white space).  If the
            return value starts with anything else it is
            silently ignored.  Generally upper case
            characters turn off a feature while lower case
            characters turn it on.  Option `S' causes the
            server not to offer STARTTLS, which is useful to
            interact with MTAs/MUAs that have broken
            STARTTLS implementations by simply not offering
            it.  `V' turns off the request for a client
            certificate during the TLS handshake.  Options
            `A' and `P' suppress SMTP AUTH and PIPELINING,
            respectively.  `c' is the equivalent to
            AuthOptions=p, i.e., it doesn't permit
            mechanisms susceptible to simple passive attack
            (e.g., PLAIN, LOGIN), unless a security layer is
            active.  Option `l' requires SMTP AUTH for a
            connection.  Options 'B', 'D', 'E', and 'X'
            suppress SMTP VERB, DSN, ETRN, and EXPN,










Sendmail Installation and Operation Guide          SMM:08-69


            respectively.

                A        Do not offer AUTH
                a        Offer AUTH (default)
                B        Do not offer VERB
                b        Offer VERB (default)
                C        Do not require security layer for
                         plaintext AUTH (default)
                c        Require security layer for plaintext AUTH
                D        Do not offer DSN
                d        Offer DSN (default)
                E        Do not offer ETRN
                e        Offer ETRN (default)
                L        Do not require AUTH (default)
                l        Require AUTH
                P        Do not offer PIPELINING
                p        Offer PIPELINING (default)
                S        Do not offer STARTTLS
                s        Offer STARTTLS (default)
                V        Do not request a client certificate
                v        Request a client certificate (default)
                X        Do not offer EXPN
                x        Offer EXPN (default)

            Note: the entries marked as ``(default)'' may
            require that some configuration has been made,
            e.g., SMTP AUTH is only available if properly
            configured.  Moreover, many options can be
            changed on a global basis via other settings as
            explained in this document, e.g., via
            DaemonPortOptions.

                 The ruleset may return `$#temp' to indicate
            that there is a temporary problem determining
            the correct features, e.g., if a map is
            unavailable.  In that case, the SMTP server
            issues a temporary failure and does not accept
            email.

         5.1.4.16.  try_tls

                 The try_tls ruleset is called when sendmail
            connects to another MTA.  If the ruleset does
            resolve to the "error" mailer, sendmail does not
            try STARTTLS even if it is offered.  This is
            useful to deal with STARTTLS interoperability
            issues by simply not using it.

         5.1.4.17.  tls_srv_features and tls_clt_features

                 The tls_clt_features ruleset is called when
            sendmail connects to another MTA and the
            tls_srv_features ruleset is called when a client










SMM:08-70          Sendmail Installation and Operation Guide


            connects to sendmail.  The arguments for the
            rulesets are the host name and IP address of the
            other side separated by $| (which is a
            metacharacter).  They should return a list of
            key=value pairs separated by semicolons; the
            list can be empty if no options should be
            applied to the connection.  Available keys are
            and their allowed values are:

            Options
              A comma separated list of SSL related options.
              See ServerSSLOptions and ClientSSLOptions for
              details, as well as SSL_set_options(3) and
              note this warning: Options already set before
              are not cleared!

            CipherList
              Specify cipher list for STARTTLS (does not
              apply to TLSv1.3), see ciphers(1) for possible
              values.  This overrides the global CipherList
              for the session.

            CertFile
              File containing a certificate.

            KeyFile
              File containing the private key for the
              certificate.

            Flags
              Currently the only valid flags are R to
              require a CRL for each encountered certificate
              during verification (by default a missing CRL
              is ignored), c and C which basically
              clears/sets the option TLSFallbacktoClear for
              just this session, respectively.

            Example:

                Stls_srv_features
                R$* $| 10.$+   $: cipherlist=HIGH


            Notes:

                 Errors in these features (e.g., unknown
            keys or invalid values) are logged and the
            current session is aborted to avoid using
            STARTTLS with features that should have been
            changed.

                 The keys are case-insensitive.











Sendmail Installation and Operation Guide          SMM:08-71


                 Both CertFile and KeyFile must be specified
            together; specifying only one is an error.

         5.1.4.18.  authinfo

                 The authinfo ruleset is called when
            sendmail tries to authenticate to another MTA.
            It should return $# followed by a list of tokens
            that are used for SMTP AUTH.  If the return
            value starts with anything else it is silently
            ignored.  Each token is a tagged string of the
            form: "TDstring" (including the quotes), where

                T        Tag which describes the item
                D        Delimiter: ':' simple text follows
                         '=' string is base64 encoded
                string   Value of the item

            Valid values for the tag are:

                U        user (authorization) id
                I        authentication id
                P        password
                R        realm
                M        list of mechanisms delimited by spaces

            If this ruleset is defined, the option
            DefaultAuthInfo is ignored (even if the ruleset
            does not return a ``useful'' result).

         5.1.4.19.  queuegroup

                 The queuegroup ruleset is used to map a
            recipient address to a queue group name.  The
            input for the ruleset is the recipient address
            (i.e., the address part of the resolved triple)
            The ruleset should return $# followed by the
            name of a queue group.  If the return value
            starts with anything else it is silently
            ignored.  See the section about ``Queue Groups
            and Queue Directories'' for further information.

         5.1.4.20.  greet_pause

                 The greet_pause ruleset is used to specify
            the amount of time to pause before sending the
            initial SMTP 220 greeting.  If any traffic is
            received during that pause, an SMTP 554
            rejection response is given instead of the 220
            greeting and all SMTP commands are rejected
            during that connection.  This helps protect
            sites from open proxies and SMTP slammers.  The
            ruleset should return $# followed by the number










SMM:08-72          Sendmail Installation and Operation Guide


            of milliseconds (thousandths of a second) to
            pause.  If the return value starts with anything
            else or is not a number, it is silently ignored.
            Note: this ruleset is not invoked (and hence the
            feature is disabled) when the smtps (SMTP over
            SSL) is used, i.e., the s modifier is set for
            the daemon via DaemonPortOptions, because in
            this case the SSL handshake is performed before
            the greeting is sent.

      5.1.5.  IPC mailers

              Some special processing occurs if the ruleset
         zero resolves to an IPC mailer (that is, a mailer
         that has "[IPC]" listed as the Path in the M
         configuration line.  The host name passed after
         "$@" has MX expansion performed if not delivering
         via a named socket; this looks the name up in DNS
         to find alternate delivery sites.

              The host name can also be provided as a dotted
         quad or an IPv6 address in square brackets; for
         example:

             [128.32.149.78]

         or

             [IPv6:2002:c0a8:51d2::23f4]

         This causes direct conversion of the numeric value
         to an IP host address.

              The host name passed in after the "$@" may
         also be a colon or comma separated list of hosts.
         Each is separately MX expanded and the results are
         concatenated to make (essentially) one long MX
         list.  Hosts separated by a comma have the same MX
         preference, and for each colon separated host the
         MX preference is increased.  The intent here is to
         create "fake" MX records that are not published in
         DNS for private internal networks.

              As a final special case, the host name can be
         passed in as a text string in square brackets:

             [ucbvax.berkeley.edu]

         This form avoids the MX mapping.  N.B.: This is
         intended only for situations where you have a
         network firewall or other host that will do special
         processing for all your mail, so that your MX
         record points to a gateway machine; this machine










Sendmail Installation and Operation Guide          SMM:08-73


         could then do direct delivery to machines within
         your local domain.  Use of this feature directly
         violates RFC 1123 section 5.3.5: it should not be
         used lightly.

   5.2.  D -- Define Macro

           Macros are named with a single character or with
      a word in {braces}.  The names ``x'' and ``{x}''
      denote the same macro for every single character
      ``x''.  Single character names may be selected from
      the entire ASCII set, but user-defined macros should
      be selected from the set of upper case letters only.
      Lower case letters and special symbols are used
      internally.  Long names beginning with a lower case
      letter or a punctuation character are reserved for use
      by sendmail, so user-defined long macro names should
      begin with an upper case letter.

           The syntax for macro definitions is:

          Dxval

      where x is the name of the macro (which may be a
      single character or a word in braces) and val is the
      value it should have.  There should be no spaces given
      that do not actually belong in the macro value.

           Macros are interpolated using the construct $x,
      where x is the name of the macro to be interpolated.
      This interpolation is done when the configuration file
      is read, except in M lines.  The special construct $&x
      can be used in R lines to get deferred interpolation.

           Conditionals can be specified using the syntax:

          $?x text1 $| text2 $.

      This interpolates text1 if the macro $x is set and
      non-null, and text2 otherwise.  The "else" ($|) clause
      may be omitted.

           The following macros are defined and/or used
      internally by sendmail for interpolation into argv's
      for mailers or for other contexts.  The ones marked *
      are information passed into sendmail[16], the ones
      marked # are information passed both in and out of
____________________
   [16]As   of   version  8.6,  all  of  these  macros  have
reasonable defaults.  Previous versions required  that  they
be defined.












SMM:08-74          Sendmail Installation and Operation Guide


      sendmail, and the unmarked macros are passed out of
      sendmail but are not otherwise used internally.  These
      macros are:

      $a   The origination date in RFC 822 format.  This is
           extracted from the Date: line.

      $b   The current date in RFC 822 format.

      $c   The hop count.  This is a count of the number of
           Received: lines plus the value of the -h command
           line flag.

      $d   The current date in UNIX (ctime) format.

      $e*  (Obsolete; use SmtpGreetingMessage option
           instead.)  The SMTP entry message.  This is
           printed out when SMTP starts up.  The first word
           must be the $j macro as specified by RFC 821.
           Defaults to "$j Sendmail $v ready at $b".
           Commonly redefined to include the configuration
           version number, e.g., "$j Sendmail $v/$Z ready at
           $b"

      $f   The envelope sender (from) address.

      $g   The sender address relative to the recipient.
           For example, if $f is "foo", $g will be
           "host!foo", "foo@host.domain", or whatever is
           appropriate for the receiving mailer.

      $h   The recipient host.  This is set in ruleset 0
           from the $@ field of a parsed address.

      $i   The queue id, e.g., "f344MXxp018717".

      $j#  The "official" domain name for this site.  This
           is fully qualified if the full qualification can
           be found.  It must be redefined to be the fully
           qualified domain name if your system is not
           configured so that information can find it
           automatically.

      $k   The UUCP node name (from the uname system call).

      $l*  (Obsolete; use UnixFromLine option instead.)  The
           format of the UNIX from line.  Unless you have
           changed the UNIX mailbox format, you should not
           change the default, which is "From $g $d".

      $m   The domain part of the gethostname return value.
           Under normal circumstances, $j is equivalent to
           $w.$m.










Sendmail Installation and Operation Guide          SMM:08-75


      $n*  The name of the daemon (for error messages).
           Defaults to "MAILER-DAEMON".

      $o*  (Obsolete: use OperatorChars option instead.)
           The set of "operators" in addresses.  A list of
           characters which will be considered tokens and
           which will separate tokens when doing parsing.
           For example, if "@" were in the $o macro, then
           the input "a@b" would be scanned as three tokens:
           "a," "@," and "b."  Defaults to ".:@[]", which is
           the minimum set necessary to do RFC 822 parsing;
           a richer set of operators is ".:%@!/[]", which
           adds support for UUCP, the %-hack, and X.400
           addresses.

      $p   Sendmail's process id.

      $q*  Default format of sender address.  The $q macro
           specifies how an address should appear in a
           message when it is defaulted.  Defaults to
           "<$g>".  It is commonly redefined to be "$?x$x
           <$g>$|$g$."  or "$g$?x ($x)$.", corresponding to
           the following two formats:

               Eric Allman <eric@CS.Berkeley.EDU>
               eric@CS.Berkeley.EDU (Eric Allman)

           Sendmail properly quotes names that have special
           characters if the first form is used.

      $r   Protocol used to receive the message.  Set from
           the -p command line flag or by the SMTP server
           code.

      $s   Sender's host name.  Set from the -p command line
           flag or by the SMTP server code (in which case it
           is set to the EHLO/HELO parameter).

      $t   A numeric representation of the current time in
           the format YYYYMMDDHHmm (4 digit year 1900-9999,
           2 digit month 01-12, 2 digit day 01-31, 2 digit
           hours 00-23, 2 digit minutes 00-59).

      $u   The recipient user.

      $v   The version number of the sendmail binary.

      $w#  The hostname of this site.  This is the root name
           of this host (but see below for caveats).

      $x   The full name of the sender.












SMM:08-76          Sendmail Installation and Operation Guide


      $z   The home directory of the recipient.

      $_   The validated sender address.  See also
           ${client_resolve}.

      ${addr_type}
           The type of the address which is currently being
           rewritten.  This macro contains up to three
           characters, the first is either `e' or `h' for
           envelope/header address, the second is a space,
           and the third is either `s' or `r' for
           sender/recipient address.

      ${alg_bits}
           The maximum keylength (in bits) of the symmetric
           encryption algorithm used for a TLS connection.
           This may be less than the effective keylength,
           which is stored in ${cipher_bits}, for ``export
           controlled'' algorithms.

      ${auth_authen}
           The client's authentication credentials as
           determined by authentication (only set if
           successful).  The format depends on the mechanism
           used, it might be just `user', or `user@realm',
           or something similar (SMTP AUTH only).

      ${auth_author}
           The authorization identity, i.e. the AUTH=
           parameter of the SMTP MAIL command if supplied.

      ${auth_type}
           The mechanism used for SMTP authentication (only
           set if successful).

      ${auth_ssf}
           The keylength (in bits) of the symmetric
           encryption algorithm used for the security layer
           of a SASL mechanism.

      ${bodytype}
           The message body type (7BIT or 8BITMIME), as
           determined from the envelope.

      ${cert_fp}
           The fingerprint of the presented certificate
           (STARTTLS only).  Note: this macro is only
           defined if the option CertFingerprintAlgorithm is
           set, in which case the specified fingerprint
           algorithm is used.  The valid algorithms depend
           on the OpenSSL version, but usually md5, sha1,
           and sha256 are available.  See











Sendmail Installation and Operation Guide          SMM:08-77


               openssl dgst -h

           for a list.

      ${cert_issuer}
           The DN (distinguished name) of the CA
           (certificate authority) that signed the presented
           certificate (the cert issuer) (STARTTLS only).

      ${cert_md5}
           The MD5 hash of the presented certificate
           (STARTTLS only).  Note: this macro is only
           defined if the option CertFingerprintAlgorithm is
           not set.

      ${cert_subject}
           The DN of the presented certificate (called the
           cert subject) (STARTTLS only).

      ${cipher}
           The cipher suite used for the connection, e.g.,
           EDH-DSS-DES-CBC3-SHA, EDH-RSA-DES-CBC-SHA, DES-
           CBC-MD5, DES-CBC3-SHA (STARTTLS only).

      ${cipher_bits}
           The effective keylength (in bits) of the
           symmetric encryption algorithm used for a TLS
           connection.

      ${client_addr}
           The IP address of the SMTP client.  IPv6
           addresses are tagged with "IPv6:" before the
           address.  Defined in the SMTP server only.

      ${client_connections}
           The number of open connections in the SMTP server
           for the client IP address.

      ${client_flags}
           The flags specified by the Modifier= part of
           ClientPortOptions where flags are separated from
           each other by spaces and upper case flags are
           doubled.  That is, Modifier=hA will be
           represented as "h AA" in ${client_flags}, which
           is required for testing the flags in rulesets.

      ${client_name}
           The host name of the SMTP client.  This may be
           the client's bracketed IP address in the form [
           nnn.nnn.nnn.nnn ] for IPv4 and [
           IPv6:nnnn:...:nnnn ] for IPv6 if the client's IP
           address is not resolvable, or if it is resolvable
           but the IP address of the resolved hostname










SMM:08-78          Sendmail Installation and Operation Guide


           doesn't match the original IP address.  Defined
           in the SMTP server only.  See also
           ${client_resolve}.

      ${client_port}
           The port number of the SMTP client.  Defined in
           the SMTP server only.

      ${client_ptr}
           The result of the PTR lookup for the client IP
           address.  Note: this is the same as
           ${client_name} if and only if ${client_resolve}
           is OK.  Defined in the SMTP server only.

      ${client_rate}
           The number of incoming connections for the client
           IP address over the time interval specified by
           ConnectionRateWindowSize.

      ${client_resolve}
           Holds the result of the resolve call for
           ${client_name}.  Possible values are:

               OK        resolved successfully
               FAIL      permanent lookup failure
               FORGED    forward lookup doesn't match reverse lookup
               TEMP      temporary lookup failure

           Defined in the SMTP server only.  sendmail
           performs a hostname lookup on the IP address of
           the connecting client.  Next the IP addresses of
           that hostname are looked up.  If the client IP
           address does not appear in that list, then the
           hostname is maybe forged.  This is reflected as
           the value FORGED for ${client_resolve} and it
           also shows up in $_ as "(may be forged)".

      ${cn_issuer}
           The CN (common name) of the CA that signed the
           presented certificate (STARTTLS only).  Note: if
           the CN cannot be extracted properly it will be
           replaced by one of these strings based on the
           encountered error:

               BadCertificateContainsNULCN contains a NUL character
               BadCertificateTooLong    CN is too long
               BadCertificateUnknown    CN could not be extracted

           In the last case, some other (unspecific) error
           occurred.

      ${cn_subject}
           The CN (common name) of the presented certificate










Sendmail Installation and Operation Guide          SMM:08-79


           (STARTTLS only).  See ${cn_issuer} for possible
           replacements.

      ${currHeader}
           Header value as quoted string (possibly truncated
           to MAXNAME).  This macro is only available in
           header check rulesets.

      ${daemon_addr}
           The IP address the daemon is listening on for
           connections.

      ${daemon_family}
           The network family if the daemon is accepting
           network connections.  Possible values include
           "inet", "inet6", "iso", "ns", "x.25"

      ${daemon_flags}
           The flags for the daemon as specified by the
           Modifier= part of DaemonPortOptions whereby the
           flags are separated from each other by spaces,
           and upper case flags are doubled.  That is,
           Modifier=Ea will be represented as "EE a" in
           ${daemon_flags}, which is required for testing
           the flags in rulesets.

      ${daemon_info}
           Some information about a daemon as a text string.
           For example, "SMTP+queueing@00:30:00".

      ${daemon_name}
           The name of the daemon from DaemonPortOptions
           Name= suboption.  If this suboption is not set,
           "Daemon#", where # is the daemon number, is used.

      ${daemon_port}
           The port the daemon is accepting connection on.
           Unless DaemonPortOptions is set, this will most
           likely be "25".

      ${deliveryMode}
           The current delivery mode sendmail is using.  It
           is initially set to the value of the DeliveryMode
           option.

      ${envid}
           The envelope id parameter (ENVID=) passed to
           sendmail as part of the envelope.

      ${hdrlen}
           The length of the header value which is stored in
           ${currHeader} (before possible truncation).  If
           this value is greater than or equal to MAXNAME










SMM:08-80          Sendmail Installation and Operation Guide


           the header has been truncated.

      ${hdr_name}
           The name of the header field for which the
           current header check ruleset has been called.
           This is useful for a default header check ruleset
           to get the name of the header; the macro is only
           available in header check rulesets.

      ${if_addr}
           The IP address of the interface of an incoming
           connection unless it is in the loopback net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.

      ${if_addr_out}
           The IP address of the interface of an outgoing
           connection unless it is in the loopback net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.

      ${if_family}
           The IP family of the interface of an incoming
           connection unless it is in the loopback net.

      ${if_family_out}
           The IP family of the interface of an outgoing
           connection unless it is in the loopback net.

      ${if_name}
           The hostname associated with the interface of an
           incoming connection.  This macro can be used for
           SmtpGreetingMessage and HReceived for virtual
           hosting.  For example:

               O SmtpGreetingMessage=$?{if_name}${if_name}$|$j$. MTA


      ${if_name_out}
           The name of the interface of an outgoing
           connection.

      ${load_avg}
           The current load average.

      ${mail_addr}
           The address part of the resolved triple of the
           address given for the SMTP MAIL command.  Defined
           in the SMTP server only.

      ${mail_host}
           The host from the resolved triple of the address
           given for the SMTP MAIL command.  Defined in the










Sendmail Installation and Operation Guide          SMM:08-81


           SMTP server only.

      ${mail_mailer}
           The mailer from the resolved triple of the
           address given for the SMTP MAIL command.  Defined
           in the SMTP server only.

      ${msg_id}
           The value of the Message-Id: header.

      ${msg_size}
           The value of the SIZE= parameter, i.e., usually
           the size of the message (in an ESMTP dialogue),
           before the message has been collected, thereafter
           the message size as computed by sendmail (and can
           be used in check_compat).

      ${nbadrcpts}
           The number of bad recipients for a single
           message.

      ${nrcpts}
           The number of validated recipients for a single
           message.  Note: since recipient validation
           happens after check_rcpt has been called, the
           value in this ruleset is one less than what might
           be expected.

      ${ntries}
           The number of delivery attempts.

      ${opMode}
           The current operation mode (from the -b flag).

      ${quarantine}
           The quarantine reason for the envelope, if it is
           quarantined.

      ${queue_interval}
           The queue run interval given by the -q flag.  For
           example, -q30m would set ${queue_interval} to
           "00:30:00".

      ${rcpt_addr}
           The address part of the resolved triple of the
           address given for the SMTP RCPT command.  Defined
           in the SMTP server only after a RCPT command.

      ${rcpt_host}
           The host from the resolved triple of the address
           given for the SMTP RCPT command.  Defined in the
           SMTP server only after a RCPT command.











SMM:08-82          Sendmail Installation and Operation Guide


      ${rcpt_mailer}
           The mailer from the resolved triple of the
           address given for the SMTP RCPT command.  Defined
           in the SMTP server only after a RCPT command.

      ${server_addr}
           The address of the server of the current outgoing
           SMTP connection.  For LMTP delivery the macro is
           set to the name of the mailer.

      ${server_name}
           The name of the server of the current outgoing
           SMTP or LMTP connection.

      ${time}
           The output of the time(3) function, i.e., the
           number of seconds since 0 hours, 0 minutes, 0
           seconds, January 1, 1970, Coordinated Universal
           Time (UTC).

      ${tls_version}
           The TLS/SSL version used for the connection,
           e.g., TLSv1.2, TLSv1; defined after STARTTLS has
           been used.

      ${total_rate}
           The total number of incoming connections over the
           time interval specified by
           ConnectionRateWindowSize.

      ${verify}
           The result of the verification of the presented
           cert; only defined after STARTTLS has been used
           (or attempted).  Possible values are:

               OK           verification succeeded.
               NO           no cert presented.
               NOT          no cert requested.
               FAIL         cert presented but could not be verified,
                            e.g., the signing CA is missing.
               NONE         STARTTLS has not been performed.
               CLEAR        STARTTLS has been disabled internally for a clear text delivery attempt.
               TEMP         temporary error occurred.
               PROTOCOL     some protocol error occurred
                            at the ESMTP level (not TLS).
               SOFTWARE     STARTTLS handshake failed,
                            which is a fatal error for this session,
                            the e-mail will be queued.


           There are three types of dates that can be used.
      The $a and $b macros are in RFC 822 format; $a is the
      time as extracted from the "Date:" line of the message










Sendmail Installation and Operation Guide          SMM:08-83


      (if there was one), and $b is the current date and
      time (used for postmarks).  If no "Date:" line is
      found in the incoming message, $a is set to the
      current time also.  The $d macro is equivalent to the
      $b macro in UNIX (ctime) format.

           The macros $w, $j, and $m are set to the identity
      of this host.  Sendmail tries to find the fully
      qualified name of the host if at all possible; it does
      this by calling gethostname(2) to get the current
      hostname and then passing that to gethostbyname(3)
      which is supposed to return the canonical version of
      that host name.[17] Assuming this is successful, $j is
      set to the fully qualified name and $m is set to the
      domain part of the name (everything after the first
      dot).  The $w macro is set to the first word
      (everything before the first dot) if you have a level
      5 or higher configuration file; otherwise, it is set
      to the same value as $j.  If the canonification is not
      successful, it is imperative that the config file set
      $j to the fully qualified domain name[18].

           The $f macro is the id of the sender as
      originally determined; when mailing to a specific host
      the $g macro is set to the address of the sender
      relative to the recipient.  For example, if I send to
      "bollard@matisse.CS.Berkeley.EDU" from the machine
      "vangogh.CS.Berkeley.EDU" the $f macro will be "eric"
      and the $g macro will be
      "eric@vangogh.CS.Berkeley.EDU."

           The $x macro is set to the full name of the
      sender.  This can be determined in several ways.  It
      can be passed as flag to sendmail.  It can be defined
      in the NAME environment variable.  The third choice is
      the value of the "Full-Name:" line in the header if it
      exists, and the fourth choice is the comment field of
      a "From:" line.  If all of these fail, and if the
      message is being originated locally, the full name is
      looked up in the /etc/passwd file.

           When sending, the $h, $u, and $z macros get set
      to the host, user, and home directory (if local) of
      the recipient.  The first two are set from the $@ and
      $: part of the rewriting rules, respectively.
____________________
   [17]For example, on some systems gethostname might return
"foo"  which   would   be   mapped   to   "foo.bar.com"   by
gethostbyname.
   [18]Older  versions  of  sendmail didn't pre-define $j at
all, so up until 8.6, config files always had to define $j.












SMM:08-84          Sendmail Installation and Operation Guide


           The $p and $t macros are used to create unique
      strings (e.g., for the "Message-Id:" field).  The $i
      macro is set to the queue id on this host; if put into
      the timestamp line it can be extremely useful for
      tracking messages.  The $v macro is set to be the
      version number of sendmail; this is normally put in
      timestamps and has been proven extremely useful for
      debugging.

           The $c field is set to the "hop count," i.e., the
      number of times this message has been processed.  This
      can be determined by the -h flag on the command line
      or by counting the timestamps in the message.

           The $r and $s fields are set to the protocol used
      to communicate with sendmail and the sending hostname.
      They can be set together using the -p command line
      flag or separately using the -M or -oM flags.

           The $_ is set to a validated sender host name.
      If the sender is running an RFC 1413 compliant IDENT
      server and the receiver has the IDENT protocol turned
      on, it will include the user name on that host.

           The ${client_name}, ${client_addr}, and
      ${client_port} macros are set to the name, address,
      and port number of the SMTP client who is invoking
      sendmail as a server.  These can be used in the
      check_* rulesets (using the $& deferred evaluation
      form, of course!).

   5.3.  C and F -- Define Classes

           Classes of phrases may be defined to match on the
      left hand side of rewriting rules, where a "phrase" is
      a sequence of characters that does not contain space
      characters.  For example a class of all local names
      for this site might be created so that attempts to
      send to oneself can be eliminated.  These can either
      be defined directly in the configuration file or read
      in from another file.  Classes are named as a single
      letter or a word in {braces}.  Class names beginning
      with lower case letters and special characters are
      reserved for system use.  Classes defined in config
      files may be given names from the set of upper case
      letters for short names or beginning with an upper
      case letter for long names.

           The syntax is:














Sendmail Installation and Operation Guide          SMM:08-85


          Ccphrase1 phrase2...
          Fcfile
          Fc|program
          Fc[mapkey]@mapclass:mapspec

      The first form defines the class c to match any of the
      named words.  If phrase1 or phrase2 is another class,
      e.g., $=S, the contents of class S are added to class
      c.  It is permissible to split them among multiple
      lines; for example, the two forms:

          CHmonet ucbmonet

      and

          CHmonet
          CHucbmonet

      are equivalent.  The ``F'' forms read the elements of
      the class c from the named file, program, or map
      specification.  Each element should be listed on a
      separate line.  To specify an optional file, use
      ``-o'' between the class name and the file name, e.g.,

          Fc -o /path/to/file

      If the file can't be used, sendmail will not complain
      but silently ignore it.  The map form should be an
      optional map key, an at sign, and a map class followed
      by the specification for that map.  Examples include:

          F{VirtHosts}@ldap:-k (&(objectClass=virtHosts)(host=*)) -v host
          F{MyClass}foo@hash:/etc/mail/classes

      will fill the class $={VirtHosts} from an LDAP map
      lookup and $={MyClass} from a hash database map lookup
      of the foo.  There is also a built-in schema that can
      be accessed by only specifying:

          F{ClassName}@LDAP

      This will tell sendmail to use the default schema:

          -k (&(objectClass=sendmailMTAClass)
               (sendmailMTAClassName=ClassName)
               (|(sendmailMTACluster=${sendmailMTACluster})
                 (sendmailMTAHost=$j)))
          -v sendmailMTAClassValue

      Note that the lookup is only done when sendmail is
      initially started.












SMM:08-86          Sendmail Installation and Operation Guide


           Elements of classes can be accessed in rules
      using $= or $~.  The $~ (match entries not in class)
      only matches a single word; multi-word entries in the
      class are ignored in this context.

           Some classes have internal meaning to sendmail:

      $=e  contains the Content-Transfer-Encodings that can
           be 8->7 bit encoded.  It is predefined to contain
           "7bit", "8bit", and "binary".

      $=k  set to be the same as $k, that is, the UUCP node
           name.

      $=m  set to the set of domains by which this host is
           known, initially just $m.

      $=n  can be set to the set of MIME body types that can
           never be eight to seven bit encoded.  It defaults
           to "multipart/signed".  Message types "message/*"
           and "multipart/*" are never encoded directly.
           Multipart messages are always handled
           recursively.  The handling of message/* messages
           are controlled by class $=s.

      $=q  A set of Content-Types that will never be encoded
           as base64 (if they have to be encoded, they will
           be encoded as quoted-printable).  It can have
           primary types (e.g., "text") or full types (such
           as "text/plain").

      $=s  contains the set of subtypes of message that can
           be treated recursively.  By default it contains
           only "rfc822".  Other "message/*" types cannot be
           8->7 bit encoded.  If a message containing eight
           bit data is sent to a seven bit host, and that
           message cannot be encoded into seven bits, it
           will be stripped to 7 bits.

      $=t  set to the set of trusted users by the T
           configuration line.  If you want to read trusted
           users from a file, use Ft/file/name.

      $=w  set to be the set of all names this host is known
           by.  This can be used to match local hostnames.

      $={persistentMacros}
           set to the macros that should be saved across
           queue runs.  Care should be taken when adding
           macro names to this class.

           Sendmail can be compiled to allow a scanf(3)
      string on the F line.  This lets you do simplistic










Sendmail Installation and Operation Guide          SMM:08-87


      parsing of text files.  For example, to read all the
      user names in your system /etc/passwd file into a
      class, use

          FL/etc/passwd %[^:]

      which reads every line up to the first colon.

   5.4.  M -- Define Mailer

           Programs and interfaces to mailers are defined in
      this line.  The format is:

          Mname, {field=value}*

      where name is the name of the mailer (used internally
      only) and the "field=name" pairs define attributes of
      the mailer.  Fields are:

          Path      The pathname of the mailer
          Flags     Special flags for this mailer
          Sender    Rewriting set(s) for sender addresses
          Recipient Rewriting set(s) for recipient addresses
          recipientsMaximum number of recipients per connection
          Argv      An argument vector to pass to this mailer
          Eol       The end-of-line string for this mailer
          Maxsize   The maximum message length to this mailer
          maxmessagesThe maximum message deliveries per connection
          Linelimit The maximum line length in the message body
          Directory The working directory for the mailer
          Userid    The default user and group id to run as
          Nice      The nice(2) increment for the mailer
          Charset   The default character set for 8-bit characters
          Type      Type information for DSN diagnostics
          Wait      The maximum time to wait for the mailer
          QueuegroupThe default queue group for the mailer
          /         The root directory for the mailer

      Only the first character of the field name is checked
      (it's case-sensitive).

           The following flags may be set in the mailer
      description.  Any other flags may be used freely to
      conditionally assign headers to messages destined for
      particular mailers.  Flags marked with * are not
      interpreted by the sendmail binary; these are the
      conventionally used to correlate to the flags portion
      of the H line.  Flags marked with # apply to the
      mailers for the sender address rather than the usual
      recipient mailers.

      a   Run Extended SMTP (ESMTP) protocol (defined in
          RFCs 1869, 1652, and 1870).  This flag defaults on










SMM:08-88          Sendmail Installation and Operation Guide


          if the SMTP greeting message includes the word
          "ESMTP".

      A   Look up the user (address) part of the resolved
          mailer triple, in the alias database.  Normally
          this is only set for local mailers.

      b   Force a blank line on the end of a message.  This
          is intended to work around some stupid versions of
          /bin/mail that require a blank line, but do not
          provide it themselves.  It would not normally be
          used on network mail.

      B   Strip leading backslashes (\) off of the address;
          this is a subset of the functionality of the s
          flag.

      c   Do not include comments in addresses.  This should
          only be used if you have to work around a remote
          mailer that gets confused by comments.  This
          strips addresses of the form "Phrase <address>" or
          "address (Comment)" down to just "address".

      C#  If mail is received from a mailer with this flag
          set, any addresses in the header that do not have
          an at sign ("@") after being rewritten by ruleset
          three will have the "@domain" clause from the
          sender envelope address tacked on.  This allows
          mail with headers of the form:

              From: usera@hosta
              To: userb@hostb, userc

          to be rewritten as:

              From: usera@hosta
              To: userb@hostb, userc@hosta

          automatically.  However, it doesn't really work
          reliably.

      d   Do not include angle brackets around route-address
          syntax addresses.  This is useful on mailers that
          are going to pass addresses to a shell that might
          interpret angle brackets as I/O redirection.
          However, it does not protect against other shell
          metacharacters.  Therefore, passing addresses to a
          shell should not be considered secure.

      D*  This mailer wants a "Date:" header line.

      e   This mailer is expensive to connect to, so try to
          avoid connecting normally; any necessary










Sendmail Installation and Operation Guide          SMM:08-89


          connection will occur during a queue run.  See
          also option HoldExpensive.

      E   Escape lines beginning with "From " in the message
          with a `>' sign.

      f   The mailer wants a -f from flag, but only if this
          is a network forward operation (i.e., the mailer
          will give an error if the executing user does not
          have special permissions).

      F*  This mailer wants a "From:" header line.

      g   Normally, sendmail sends internally generated
          email (e.g., error messages) using the null return
          address as required by RFC 1123.  However, some
          mailers don't accept a null return address.  If
          necessary, you can set the g flag to prevent
          sendmail from obeying the standards; error
          messages will be sent as from the MAILER-DAEMON
          (actually, the value of the $n macro).

      h   Upper case should be preserved in host names (the
          $@ portion of the mailer triplet resolved from
          ruleset 0) for this mailer.

      i   Do User Database rewriting on envelope sender
          address.

      I   This flag is deprecated and will be removed from a
          future version.  This mailer will be speaking SMTP
          to another sendmail -- as such it can use special
          protocol features.  This flag should not be used
          except for debugging purposes because it uses VERB
          as SMTP command.

      j   Do User Database rewriting on recipients as well
          as senders.

      k   Normally when sendmail connects to a host via
          SMTP, it checks to make sure that this isn't
          accidentally the same host name as might happen if
          sendmail is misconfigured or if a long-haul
          network interface is set in loopback mode.  This
          flag disables the loopback check.  It should only
          be used under very unusual circumstances.

      K   Currently unimplemented.  Reserved for chunking.

      l   This mailer is local (i.e., final delivery will be
          performed).












SMM:08-90          Sendmail Installation and Operation Guide


      L   Limit the line lengths as specified in RFC 821.
          This deprecated option should be replaced by the
          L= mail declaration.  For historic reasons, the L
          flag also sets the 7 flag.

      m   This mailer can send to multiple users on the same
          host in one transaction.  When a $u macro occurs
          in the argv part of the mailer definition, that
          field will be repeated as necessary for all
          qualifying users.  Removing this flag can defeat
          duplicate suppression on a remote site as each
          recipient is sent in a separate transaction.

      M*  This mailer wants a "Message-Id:" header line.

      n   Do not insert a UNIX-style "From" line on the
          front of the message.

      o   Always run as the owner of the recipient mailbox.
          Normally sendmail runs as the sender for locally
          generated mail or as "daemon" (actually, the user
          specified in the u option) when delivering network
          mail.  The normal behavior is required by most
          local mailers, which will not allow the envelope
          sender address to be set unless the mailer is
          running as daemon.  This flag is ignored if the S
          flag is set.

      p   Use the route-addr style reverse-path in the SMTP
          "MAIL FROM:" command rather than just the return
          address; although this is required in RFC 821
          section 3.1, many hosts do not process reverse-
          paths properly.  Reverse-paths are officially
          discouraged by RFC 1123.

      P*  This mailer wants a "Return-Path:" line.

      q   When an address that resolves to this mailer is
          verified (SMTP VRFY command), generate 250
          responses instead of 252 responses.  This will
          imply that the address is local.

      r   Same as f, but sends a -r flag.

      R   Open SMTP connections from a "secure" port.
          Secure ports aren't (secure, that is) except on
          UNIX machines, so it is unclear that this adds
          anything.  sendmail must be running as root to be
          able to use this flag.

      s   Strip quote characters (" and \) off of the
          address before calling the mailer.











Sendmail Installation and Operation Guide          SMM:08-91


      S   Don't reset the userid before calling the mailer.
          This would be used in a secure environment where
          sendmail ran as root.  This could be used to avoid
          forged addresses.  If the U= field is also
          specified, this flag causes the effective user id
          to be set to that user.

      u   Upper case should be preserved in user names for
          this mailer.  Standards require preservation of
          case in the local part of addresses, except for
          those address for which your system accepts
          responsibility.  RFC 2142 provides a long list of
          addresses which should be case insensitive.  If
          you use this flag, you may be violating RFC 2142.
          Note that postmaster is always treated as a case
          insensitive address regardless of this flag.

      U   This mailer wants UUCP-style "From" lines with the
          ugly "remote from <host>" on the end.

      w   The user must have a valid account on this
          machine, i.e., getpwnam must succeed.  If not, the
          mail is bounced.  See also the MailBoxDatabase
          option.  This is required to get ".forward"
          capability.

      W   Ignore long term host status information (see
          Section "Persistent Host Status Information").

      x*  This mailer wants a "Full-Name:" header line.

      X   This mailer wants to use the hidden dot algorithm
          as specified in RFC 821; basically, any line
          beginning with a dot will have an extra dot
          prepended (to be stripped at the other end).  This
          insures that lines in the message containing a dot
          will not terminate the message prematurely.

      z   Run Local Mail Transfer Protocol (LMTP) between
          sendmail and the local mailer.  This is a variant
          on SMTP defined in RFC 2033 that is specifically
          designed for delivery to a local mailbox.

      Z   Apply DialDelay (if set) to this mailer.

      0   Don't look up MX records for hosts sent via
          SMTP/LMTP.  Do not apply FallbackMXhost either.

      1   Don't send null characters ('\0') to this mailer.

      2   Don't use ESMTP even if offered; this is useful
          for broken systems that offer ESMTP but fail on
          EHLO (without recovering when HELO is tried next).










SMM:08-92          Sendmail Installation and Operation Guide


      3   Extend the list of characters converted to =XX
          notation when converting to Quoted-Printable to
          include those that don't map cleanly between ASCII
          and EBCDIC.  Useful if you have IBM mainframes on
          site.

      5   If no aliases are found for this address, pass the
          address through ruleset 5 for possible alternate
          resolution.  This is intended to forward the mail
          to an alternate delivery spot.

      6   Strip headers to seven bits.

      7   Strip all output to seven bits.  This is the
          default if the L flag is set.  Note that clearing
          this option is not sufficient to get full eight
          bit data passed through sendmail.  If the 7 option
          is set, this is essentially always set, since the
          eighth bit was stripped on input.  Note that this
          option will only impact messages that didn't have
          8->7 bit MIME conversions performed.

      8   If set, it is acceptable to send eight bit data to
          this mailer; the usual attempt to do 8->7 bit MIME
          conversions will be bypassed.

      9   If set, do limited 7->8 bit MIME conversions.
          These conversions are limited to text/plain data.

      :   Check addresses to see if they begin ":include:";
          if they do, convert them to the "*include*"
          mailer.

      |   Check addresses to see if they begin with a `|';
          if they do, convert them to the "prog" mailer.

      /   Check addresses to see if they begin with a `/';
          if they do, convert them to the "*file*" mailer.

      @   Look up addresses in the user database.

      %   Do not attempt delivery on initial receipt of a
          message or on queue runs unless the queued message
          is selected using one of the -qI/-qR/-qS queue run
          modifiers or an ETRN request.

      !   Disable an MH hack that drops an explicit From:
          header if it is the same as what sendmail would
          generate.

           Configuration files prior to level 6 assume the
      `A', `w', `5', `:', `|', `/', and `@' options on the
      mailer named "local".










Sendmail Installation and Operation Guide          SMM:08-93


           The mailer with the special name "error" can be
      used to generate a user error.  The (optional) host
      field is an exit status to be returned, and the user
      field is a message to be printed.  The exit status may
      be numeric or one of the values USAGE, NOUSER, NOHOST,
      UNAVAILABLE, SOFTWARE, TEMPFAIL, PROTOCOL, or CONFIG
      to return the corresponding EX_ exit code, or an
      enhanced error code as described in RFC 1893, Enhanced
      Mail System Status Codes.  For example, the entry:

          $#error $@ NOHOST $: Host unknown in this domain

      on the RHS of a rule will cause the specified error to
      be generated and the "Host unknown" exit status to be
      returned if the LHS matches.  This mailer is only
      functional in rulesets 0, 5, or one of the check_*
      rulesets.  The host field can also contain the special
      token quarantine which instructs sendmail to
      quarantine the current message.

           The mailer with the special name "discard" causes
      any mail sent to it to be discarded but otherwise
      treated as though it were successfully delivered.
      This mailer cannot be used in ruleset 0, only in the
      various address checking rulesets.

           The mailer named "local" must be defined in every
      configuration file.  This is used to deliver local
      mail, and is treated specially in several ways.
      Additionally, three other mailers named "prog",
      "*file*", and "*include*" may be defined to tune the
      delivery of messages to programs, files, and :include:
      lists respectively.  They default to:

          Mprog, P=/bin/sh, F=lsoDq9, T=DNS/RFC822/X-Unix, A=sh -c $u
          M*file*, P=[FILE], F=lsDFMPEouq9, T=DNS/RFC822/X-Unix, A=FILE $u
          M*include*, P=/dev/null, F=su, A=INCLUDE $u


           Builtin pathnames are [FILE] and [IPC], the
      former is used for delivery to files, the latter for
      delivery via interprocess communication.  For mailers
      that use [IPC] as pathname the argument vector (A=)
      must start with TCP or FILE for delivery via a TCP or
      a Unix domain socket.  If TCP is used, the second
      argument must be the name of the host to contact.
      Optionally a third argument can be used to specify a
      port, the default is smtp (port 25).  If FILE is used,
      the second argument must be the name of the Unix
      domain socket.

           If the argument vector does not contain $u then
      sendmail will speak SMTP (or LMTP if the mailer flag z










SMM:08-94          Sendmail Installation and Operation Guide


      is specified) to the mailer.

           If no Eol field is defined, then the default is
      "\r\n" for SMTP mailers and "\n" of others.

           The Sender and Recipient rewriting sets may
      either be a simple ruleset id or may be two ids
      separated by a slash; if so, the first rewriting set
      is applied to envelope addresses and the second is
      applied to headers.  Setting any value to zero
      disables corresponding mailer-specific rewriting.

           The Directory is actually a colon-separated path
      of directories to try.  For example, the definition
      "D=$z:/" first tries to execute in the recipient's
      home directory; if that is not available, it tries to
      execute in the root of the filesystem.  This is
      intended to be used only on the "prog" mailer, since
      some shells (such as csh) refuse to execute if they
      cannot read the current directory.  Since the queue
      directory is not normally readable by unprivileged
      users csh scripts as recipients can fail.

           The Userid specifies the default user and group
      id to run as, overriding the DefaultUser option
      (q.v.).  If the S mailer flag is also specified, this
      user and group will be set as the effective uid and
      gid for the process.  This may be given as user:group
      to set both the user and group id; either may be an
      integer or a symbolic name to be looked up in the
      passwd and group files respectively.  If only a
      symbolic user name is specified, the group id in the
      passwd file for that user is used as the group id.

           The Charset field is used when converting a
      message to MIME; this is the character set used in the
      Content-Type: header.  If this is not set, the
      DefaultCharset option is used, and if that is not set,
      the value "unknown-8bit" is used.  WARNING: this field
      applies to the sender's mailer, not the recipient's
      mailer.  For example, if the envelope sender address
      lists an address on the local network and the
      recipient is on an external network, the character set
      will be set from the Charset= field for the local
      network mailer, not that of the external network
      mailer.

           The Type= field sets the type information used in
      MIME error messages as defined by RFC 1894.  It is
      actually three values separated by slashes: the MTA-
      type (that is, the description of how hosts are
      named), the address type (the description of e-mail
      addresses), and the diagnostic type (the description










Sendmail Installation and Operation Guide          SMM:08-95


      of error diagnostic codes).  Each of these must be a
      registered value or begin with "X-".  The default is
      "dns/rfc822/smtp".

           The m= field specifies the maximum number of
      messages to attempt to deliver on a single SMTP or
      LMTP connection.  The default is infinite.

           The r= field specifies the maximum number of
      recipients to attempt to deliver in a single envelope.
      It defaults to 100.

           The /= field specifies a new root directory for
      the mailer.  The path is macro expanded and then
      passed to the "chroot" system call.  The root
      directory is changed before the Directory field is
      consulted or the uid is changed.

           The Wait= field specifies the maximum time to
      wait for the mailer to return after sending all data
      to it.  This applies to mailers that have been forked
      by sendmail.

           The Queuegroup= field specifies the default queue
      group in which received mail should be queued.  This
      can be overridden by other means as explained in
      section ``Queue Groups and Queue Directories''.

   5.5.  H -- Define Header

           The format of the header lines that sendmail
      inserts into the message are defined by the H line.
      The syntax of this line is one of the following:

          Hhname: htemplate


          H[?mflags?]hname: htemplate


          H[?${macro}?]hname: htemplate

      Continuation lines in this spec are reflected directly
      into the outgoing message.  The htemplate is macro-
      expanded before insertion into the message.  If the
      mflags (surrounded by question marks) are specified,
      at least one of the specified flags must be stated in
      the mailer definition for this header to be
      automatically output.  If a ${macro} (surrounded by
      question marks) is specified, the header will be
      automatically output if the macro is set.  The macro
      may be set using any of the normal methods, including
      using the macro storage map in a ruleset.  If one of










SMM:08-96          Sendmail Installation and Operation Guide


      these headers is in the input it is reflected to the
      output regardless of these flags or macros.  Notice:
      If a ${macro} is used to set a header, then it is
      useful to add that macro to class $={persistentMacros}
      which consists of the macros that should be saved
      across queue runs.

           Some headers have special semantics that will be
      described later.

           A secondary syntax allows validation of headers
      as they are being read.  To enable validation, use:

          HHeader: $>Ruleset
          HHeader: $>+Ruleset

      The indicated Ruleset is called for the specified
      Header, and can return $#error to reject or quarantine
      the message or $#discard to discard the message (as
      with the other check_* rulesets).  The ruleset
      receives the header field-body as argument, i.e., not
      the header field-name; see also ${hdr_name} and
      ${currHeader}.  The header is treated as a structured
      field, that is, text in parentheses is deleted before
      processing, unless the second form $>+ is used.  Note:
      only one ruleset can be associated with a header;
      sendmail will silently ignore multiple entries.

           For example, the configuration lines:

          HMessage-Id: $>CheckMessageId

          SCheckMessageId
          R< $+ @ $+  >$@ OK
          R$*       $#error $: Illegal Message-Id header

      would refuse any message that had a Message-Id: header
      of any of the following forms:

          Message-Id: <>
          Message-Id: some text
          Message-Id: <legal text@domain> extra crud

      A default ruleset that is called for headers which
      don't have a specific ruleset defined for them can be
      specified by:

          H*: $>Ruleset

      or

          H*: $>+Ruleset











Sendmail Installation and Operation Guide          SMM:08-97


   5.6.  O -- Set Option

           There are a number of global options that can be
      set from a configuration file.  Options are
      represented by full words; some are also representable
      as single characters for back compatibility.  The
      syntax of this line is:

          O  option=value

      This sets option option to be value.  Note that there
      must be a space between the letter `O' and the name of
      the option.  An older version is:

          Oovalue

      where the option o is a single character.  Depending
      on the option, value may be a string, an integer, a
      boolean (with legal values "t", "T", "f", or "F"; the
      default is TRUE), or a time interval.

           All filenames used in options should be absolute
      paths, i.e., starting with '/'.  Relative filenames
      most likely cause surprises during operation (unless
      otherwise noted).

           The options supported (with the old, one
      character names in brackets) are:

      AliasFile=spec, spec, ...
                [A] Specify possible alias file(s).  Each
                spec should be in the format ``class: info''
                where class: is optional and defaults to
                ``implicit''.  Note that info is required
                for all classes except "ldap".  For the
                "ldap" class, if info is not specified, a
                default info value is used as follows:

                    -k (&(objectClass=sendmailMTAAliasObject)
                         (sendmailMTAAliasName=aliases)
                         (|(sendmailMTACluster=${sendmailMTACluster})
                           (sendmailMTAHost=$j))
                         (sendmailMTAKey=%0))
                    -v sendmailMTAAliasValue

                Depending on how sendmail is compiled, valid
                classes are "implicit" (search through a
                compiled-in list of alias file types, for
                back compatibility), "hash" (if NEWDB is
                specified), "btree" (if NEWDB is specified),
                "dbm" (if NDBM is specified), "cdb" (if CDB
                is specified), "stab" (internal symbol table
                -- not normally used unless you have no










SMM:08-98          Sendmail Installation and Operation Guide


                other database lookup), "sequence" (use a
                sequence of maps previously declared),
                "ldap" (if LDAPMAP is specified), or "nis"
                (if NIS is specified).  If a list of specs
                are provided, sendmail searches them in
                order.

      AliasWait=timeout
                [a] If set, wait up to timeout (units
                default to minutes) for an "@:@" entry to
                exist in the alias database before starting
                up.  If it does not appear in the timeout
                interval issue a warning.

      AllowBogusHELO
                [no short name] If set, allow HELO SMTP
                commands that don't include a host name.
                Setting this violates RFC 1123 section
                5.2.5, but is necessary to interoperate with
                several SMTP clients.  If there is a value,
                it is still checked for legitimacy.

      AuthMaxBits=N
                [no short name] Limit the maximum encryption
                strength for the security layer in SMTP AUTH
                (SASL). Default is essentially unlimited.
                This allows to turn off additional
                encryption in SASL if STARTTLS is already
                encrypting the communication, because the
                existing encryption strength is taken into
                account when choosing an algorithm for the
                security layer.  For example, if STARTTLS is
                used and the symmetric cipher is 3DES, then
                the the keylength (in bits) is 168.  Hence
                setting AuthMaxBits to 168 will disable any
                encryption in SASL.

      AuthMechanisms
                [no short name] List of authentication
                mechanisms for AUTH (separated by spaces).
                The advertised list of authentication
                mechanisms will be the intersection of this
                list and the list of available mechanisms as
                determined by the Cyrus SASL library.  If
                STARTTLS is active, EXTERNAL will be added
                to this list.  In that case, the value of
                {cert_subject} is used as authentication id.

      AuthOptions
                [no short name] List of options for SMTP
                AUTH consisting of single characters with
                intervening white space or commas.











Sendmail Installation and Operation Guide          SMM:08-99


                    A   Use the AUTH= parameter for the MAIL FROM
                        command only when authentication succeeded.
                        This can be used as a workaround for broken
                        MTAs that do not implement RFC 2554 correctly.
                    a   protection from active (non-dictionary) attacks
                        during authentication exchange.
                    c   require mechanisms which pass client credentials,
                        and allow mechanisms which can pass credentials
                        to do so.
                    d   don't permit mechanisms susceptible to passive
                        dictionary attack.
                    f   require forward secrecy between sessions
                        (breaking one won't help break next).
                    m   require mechanisms which provide mutual authentication
                        (only available if using Cyrus SASL v2 or later).
                    p   don't permit mechanisms susceptible to simple
                        passive attack (e.g., PLAIN, LOGIN), unless a
                        security layer is active.
                    y   don't permit mechanisms that allow anonymous login.

                The first option applies to sendmail as a
                client, the others to a server.  Example:

                    O AuthOptions=p,y

                would disallow ANONYMOUS as AUTH mechanism
                and would allow PLAIN and LOGIN only if a
                security layer (e.g., provided by STARTTLS)
                is already active.  The options 'a', 'c',
                'd', 'f', 'p', and 'y' refer to properties
                of the selected SASL mechanisms.
                Explanations of these properties can be
                found in the Cyrus SASL documentation.

      AuthRealm [no short name] The authentication realm
                that is passed to the Cyrus SASL library.
                If no realm is specified, $j is used.  See
                also KNOWNBUGS.

      BadRcptThrottle=N
                [no short name] If set and the specified
                number of recipients in a single SMTP
                transaction have been rejected, sleep for
                one second after each subsequent RCPT
                command in that transaction.

      BlankSub=c
                [B] Set the blank substitution character to
                c.  Unquoted spaces in addresses are
                replaced by this character.  Defaults to
                space (i.e., no change is made).












SMM:08-100         Sendmail Installation and Operation Guide


      CACertPath
                [no short name] Path to directory with
                certificates of CAs.  This directory
                directory must contain the hashes of each CA
                certificate as filenames (or as links to
                them).

      CACertFile
                [no short name] File containing one or more
                CA certificates; see section about STARTTLS
                for more information.

      CertFingerprintAlgorithm
                Specify the fingerprint algorithm (digest)
                to use for the presented cert.  If the
                option is not set, md5 is used and the macro
                ${cert_md5} contains the cert fingerprint.
                If the option is explicitly set, the
                specified algorithm (e.g., sha1) is used and
                the macro ${cert_fp} contains the cert
                fingerprint.

      CipherList
                Specify cipher list for STARTTLS (does not
                apply to TLSv1.3).  See ciphers(1) for
                possible values.

      CheckAliases
                [n] Validate the RHS of aliases when
                rebuilding the alias database.

      CheckpointInterval=N
                [C] Checkpoints the queue every N (default
                10) addresses sent.  If your system crashes
                during delivery to a large list, this
                prevents retransmission to any but the last
                N recipients.

      ClassFactor=fact
                [z] The indicated factor is multiplied by
                the message class (determined by the
                Precedence: field in the user header and the
                P lines in the configuration file) and
                subtracted from the priority.  Thus,
                messages with a higher Priority: will be
                favored.  Defaults to 1800.

      ClientCertFile
                [no short name] File containing the
                certificate of the client, i.e., this
                certificate is used when sendmail acts as
                client (for STARTTLS).











Sendmail Installation and Operation Guide         SMM:08-101


      ClientKeyFile
                [no short name] File containing the private
                key belonging to the client certificate (for
                STARTTLS if sendmail runs as client).

      ClientPortOptions=options
                [O] Set client SMTP options.  The options
                are key=value pairs separated by commas.
                Known keys are:

                    Port      Name/number of source port for connection (defaults to any free port)
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer
                    Modifier  Options (flags) for the client

                The Address mask may be a numeric address in
                IPv4 dot notation or IPv6 colon notation or
                a network name.  Note that if a network name
                is specified, only the first IP address
                returned for it will be used.  This may
                cause indeterminate behavior for network
                names that resolve to multiple addresses.
                Therefore, use of an address is recommended.
                Modifier can be the following character:

                    h         use name of interface for HELO command
                    A         don't use AUTH when sending e-mail
                    S         don't use STARTTLS when sending e-mail

                If ``h'' is set, the name corresponding to
                the outgoing interface address (whether
                chosen via the Connection parameter or the
                default) is used for the HELO/EHLO command.
                However, the name must not start with a
                square bracket and it must contain at least
                one dot.  This is a simple test whether the
                name is not an IP address (in square
                brackets) but a qualified hostname.  Note
                that multiple ClientPortOptions settings are
                allowed in order to give settings for each
                protocol family (e.g., one for Family=inet
                and one for Family=inet6).  A restriction
                placed on one family only affects outgoing
                connections on that particular family.

      ClientSSLOptions
                A space or comma separated list of SSL
                related options for the client side.  See
                SSL_CTX_set_options(3) for a list; the
                available values depend on the OpenSSL
                version against which sendmail is compiled.










SMM:08-102         Sendmail Installation and Operation Guide


                By default, SSL_OP_ALL SSL_OP_NO_SSLv2
                SSL_OP_NO_TICKET -SSL_OP_TLSEXT_PADDING are
                used (if those options are available).
                Options can be cleared by preceding them
                with a minus sign.  It is also possible to
                specify numerical values, e.g., -0x0010.

      ColonOkInAddr
                [no short name] If set, colons are
                acceptable in e-mail addresses (e.g.,
                "host:user").  If not set, colons indicate
                the beginning of a RFC 822 group construct
                ("groupname: member1, member2, ...
                memberN;").  Doubled colons are always
                acceptable ("nodename::user") and proper
                route-addr nesting is understood
                ("<@relay:user@host>").  Furthermore, this
                option defaults on if the configuration
                version level is less than 6 (for back
                compatibility).  However, it must be off for
                full compatibility with RFC 822.

      ConnectionCacheSize=N
                [k] The maximum number of open connections
                that will be cached at a time.  The default
                is one.  This delays closing the current
                connection until either this invocation of
                sendmail needs to connect to another host or
                it terminates.  Setting it to zero defaults
                to the old behavior, that is, connections
                are closed immediately.  Since this consumes
                file descriptors, the connection cache
                should be kept small: 4 is probably a
                practical maximum.

      ConnectionCacheTimeout=timeout
                [K] The maximum amount of time a cached
                connection will be permitted to idle without
                activity.  If this time is exceeded, the
                connection is immediately closed.  This
                value should be small (on the order of ten
                minutes).  Before sendmail uses a cached
                connection, it always sends a RSET command
                to check the connection; if this fails, it
                reopens the connection.  This keeps your end
                from failing if the other end times out.
                The point of this option is to be a good
                network neighbor and avoid using up
                excessive resources on the other end.  The
                default is five minutes.

      ConnectOnlyTo=address
                [no short name] This can be used to override










Sendmail Installation and Operation Guide         SMM:08-103


                the connection address (for testing
                purposes).

      ConnectionRateThrottle=N
                [no short name] If set to a positive value,
                allow no more than N incoming connections in
                a one second period per daemon.  This is
                intended to flatten out peaks and allow the
                load average checking to cut in.  Defaults
                to zero (no limits).

      ConnectionRateWindowSize=N
                [no short name] Define the length of the
                interval for which the number of incoming
                connections is maintained.  The default is
                60 seconds.

      ControlSocketName=name
                [no short name] Name of the control socket
                for daemon management.  A running sendmail
                daemon can be controlled through this named
                socket.  Available commands are: help,
                mstat, restart, shutdown, and status.  The
                status command returns the current number of
                daemon children, the maximum number of
                daemon children, the free disk space (in
                blocks) of the queue directory, and the load
                average of the machine expressed as an
                integer.  If not set, no control socket will
                be available.  Solaris and pre-4.4BSD kernel
                users should see the note in sendmail/README
                .

      CRLFile=name
                [no short name] Name of file that contains
                certificate revocation status, useful for
                X.509v3 authentication.  Note: if a CRLFile
                is specified but the file is unusable,
                STARTTLS is disabled.

      CRLPath=name
                [no short name] Name of directory that
                contains hashes pointing to certificate
                revocation status files.  Symbolic links can
                be generated with the following two (Bourne)
                shell commands:

                    C=FileName_of_CRL
                    ln -s $C `openssl crl -noout -hash < $C`.r0


      DHParameters
                This option applies to the server side only.










SMM:08-104         Sendmail Installation and Operation Guide


                Possible values are:

                    5                   use precomputed 512 bit prime.
                    1                   generate 1024 bit prime
                    2                   generate 2048 bit prime.
                    i                   use included precomputed 2048 bit prime (default).
                    none                do not use Diffie-Hellman.
                    /path/to/file       load prime from file.

                This is only required if a ciphersuite
                containing DSA/DH is used.  The default is
                ``i'' which selects a precomputed, fixed
                2048 bit prime.  If ``5'' is selected, then
                precomputed, fixed primes are used.  Note:
                this option should not be used (unless
                necessary for compatibility with old
                implementations).  If ``1'' or ``2'' is
                selected, then prime values are computed
                during startup.  Note: this operation can
                take a significant amount of time on a slow
                machine (several seconds), but it is only
                done once at startup.  If ``none'' is
                selected, then TLS ciphersuites containing
                DSA/DH cannot be used.  If a file name is
                specified (which must be an absolute path),
                then the primes are read from it.  It is
                recommended to generate such a file using a
                command like this:

                                        openssl dhparam -out /etc/mail/dhparams.pem 2048

                If the file is not readable or contains
                unusable data, the default ``i'' is used
                instead.

      DaemonPortOptions=options
                [O] Set server SMTP options.  Each instance
                of DaemonPortOptions leads to an additional
                incoming socket.  The options are key=value
                pairs.  Known keys are:























Sendmail Installation and Operation Guide         SMM:08-105


                    Name      User-definable name for the daemon (defaults to "Daemon#")
                    Port      Name/number of listening port (defaults to "smtp")
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    InputMailFiltersList of input mail filters for the daemon
                    Listen    Size of listen queue (defaults to 10)
                    Modifier  Options (flags) for the daemon
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer
                    children  maximum number of children per daemon, see MaxDaemonChildren.
                    DeliveryModeDelivery mode per daemon, see DeliveryMode.
                    refuseLA  RefuseLA per daemon
                    delayLA   DelayLA per daemon
                    queueLA   QueueLA per daemon

                The Name key is used for error messages and
                logging.  The Address mask may be a numeric
                address in IPv4 dot notation or IPv6 colon
                notation, or a network name, or a path to a
                local socket.  Note that if a network name
                is specified, only the first IP address
                returned for it will be used.  This may
                cause indeterminate behavior for network
                names that resolve to multiple addresses.
                Therefore, use of an address is recommended.
                The Family key defaults to INET (IPv4).
                IPv6 users who wish to also accept IPv6
                connections should add additional
                Family=inet6 DaemonPortOptions lines.  For a
                local socket, use Family=local or
                Family=unix.  The InputMailFilters key
                overrides the default list of input mail
                filters listed in the InputMailFilters
                option.  If multiple input mail filters are
                required, they must be separated by
                semicolons (not commas).  Modifier can be a
                sequence (without any delimiters) of the
                following characters:

                    a         always require authentication
                    b         bind to interface through which mail has been received
                    c         perform hostname canonification (.cf)
                    f         require fully qualified hostname (.cf)
                    s         Run smtps (SMTP over SSL) instead of smtp
                    u         allow unqualified addresses (.cf)
                    A         disable AUTH (overrides 'a' modifier)
                    C         don't perform hostname canonification
                    E         disallow ETRN (see RFC 2476)
                    O         optional; if opening the socket fails ignore it
                    S         don't offer STARTTLS

                That is, one way to specify a message
                submission agent (MSA) that always requires










SMM:08-106         Sendmail Installation and Operation Guide


                authentication is:

                    O DaemonPortOptions=Name=MSA, Port=587, M=Ea

                The modifiers that are marked with "(.cf)"
                have only effect in the standard
                configuration file, in which they are
                available via ${daemon_flags}.  Notice: Do
                not use the ``a'' modifier on a public
                accessible MTA!  It should only be used for
                a MSA that is accessed by authorized users
                for initial mail submission.  Users must
                authenticate to use a MSA which has this
                option turned on.  The flags ``c'' and ``C''
                can change the default for hostname
                canonification in the sendmail.cf file.  See
                the relevant documentation for
                FEATURE(nocanonify).  The modifier ``f''
                disallows addresses of the form user@host
                unless they are submitted directly.  The
                flag ``u'' allows unqualified sender
                addresses, i.e., those without @host.  ``b''
                forces sendmail to bind to the interface
                through which the e-mail has been received
                for the outgoing connection.  WARNING: Use
                ``b'' only if outgoing mail can be routed
                through the incoming connection's interface
                to its destination. No attempt is made to
                catch problems due to a misconfiguration of
                this parameter, use it only for virtual
                hosting where each virtual interface can
                connect to every possible location.  This
                will also override possible settings via
                ClientPortOptions.  Note, sendmail will
                listen on a new socket for each occurrence
                of the DaemonPortOptions option in a
                configuration file.  The modifier ``O''
                causes sendmail to ignore a socket if it
                can't be opened.  This applies to failures
                from the socket(2) and bind(2) calls.

      DefaultAuthInfo
                [no short name] Filename that contains
                default authentication information for
                outgoing connections. This file must contain
                the user id, the authorization id, the
                password (plain text), the realm and the
                list of mechanisms to use on separate lines
                and must be readable by root (or the trusted
                user) only.  If no realm is specified, $j is
                used.  If no mechanisms are specified, the
                list given by AuthMechanisms is used.
                Notice: this option is deprecated and will










Sendmail Installation and Operation Guide         SMM:08-107


                be removed in future versions.  Moreover, it
                doesn't work for the MSP since it can't read
                the file (the file must not be group/world-
                readable otherwise sendmail will complain).
                Use the authinfo ruleset instead which
                provides more control over the usage of the
                data anyway.

      DefaultCharSet=charset
                [no short name] When a message that has
                8-bit characters but is not in MIME format
                is converted to MIME (see the EightBitMode
                option) a character set must be included in
                the Content-Type: header.  This character
                set is normally set from the Charset= field
                of the mailer descriptor.  If that is not
                set, the value of this option is used.  If
                this option is not set, the value
                "unknown-8bit" is used.

      DataFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before a memory-based queue data file
                becomes disk-based.  The default is 4096
                bytes.

      DeadLetterDrop=file
                [no short name] Defines the location of the
                system-wide dead.letter file, formerly
                hardcoded to /usr/tmp/dead.letter.  If this
                option is not set (the default), sendmail
                will not attempt to save to a system-wide
                dead.letter file in the event it cannot
                bounce the mail to the user or postmaster.
                Instead, it will rename the qf file as it
                has in the past when the dead.letter file
                could not be opened.

      DefaultUser=user:group
                [u] Set the default userid for mailers to
                user:group.  If group is omitted and user is
                a user name (as opposed to a numeric user
                id) the default group listed in the
                /etc/passwd file for that user is used as
                the default group.  Both user and group may
                be numeric.  Mailers without the S flag in
                the mailer definition will run as this user.
                Defaults to 1:1.  The value can also be















SMM:08-108         Sendmail Installation and Operation Guide


                given as a symbolic user name.[19]

      DelayLA=LA
                [no short name] When the system load average
                exceeds LA, sendmail will sleep for one
                second on most SMTP commands and before
                accepting connections.

      DeliverByMin=time
                [0] Set minimum time for Deliver By SMTP
                Service Extension (RFC 2852).  If 0, no time
                is listed, if less than 0, the extension is
                not offered, if greater than 0, it is listed
                as minimum time for the EHLO keyword
                DELIVERBY.

      DeliveryMode=x
                [d] Deliver in mode x.  Legal modes are:

                    i   Deliver interactively (synchronously)
                    b   Deliver in background (asynchronously)
                    q   Just queue the message (deliver during queue run)
                    d   Defer delivery and all map lookups (deliver during queue run)

                Defaults to ``b'' if no option is specified,
                ``i'' if it is specified but given no
                argument (i.e., ``Od'' is equivalent to
                ``Odi'').  The -v command line flag sets
                this to i.  Note: for internal reasons,
                ``i'' does not work if a milter is enabled
                which can reject or delete recipients.  In
                that case the mode will be changed to ``b''.

      DialDelay=sleeptime
                [no short name] Dial-on-demand network
                connections can see timeouts if a connection
                is opened before the call is set up.  If
                this is set to an interval and a connection
                times out on the first connection being
                attempted sendmail will sleep for this
                amount of time and try again.  This should
                give your system time to establish the
                connection to your service provider.  Units
                default to seconds, so "DialDelay=5" uses a
                five second delay.  Defaults to zero (no
                retry).  This delay only applies to mailers
                which have the Z flag set.


____________________
   [19]The   old   g  option  has  been  combined  into  the
DefaultUser option.











Sendmail Installation and Operation Guide         SMM:08-109


      DirectSubmissionModifiers=modifiers
                Defines ${daemon_flags} for direct (command
                line) submissions.  If not set,
                ${daemon_flags} is either "CC f" if the
                option -G is used or "c u" otherwise.  Note
                that only the the "CC", "c", "f", and "u"
                flags are checked.

      DontBlameSendmail=option,option,...
                [no short name] In order to avoid possible
                cracking attempts caused by world- and
                group-writable files and directories,
                sendmail does paranoid checking when opening
                most of its support files.  If for some
                reason you absolutely must run with, for
                example, a group-writable /etc directory,
                then you will have to turn off this checking
                (at the cost of making your system more
                vulnerable to attack).  The possible
                arguments have been described earlier.  The
                details of these flags are described above.
                Use of this option is not recommended.

      DontExpandCnames
                [no short name] The standards say that all
                host addresses used in a mail message must
                be fully canonical.  For example, if your
                host is named "Cruft.Foo.ORG" and also has
                an alias of "FTP.Foo.ORG", the former name
                must be used at all times.  This is enforced
                during host name canonification ($[ ... $]
                lookups).  If this option is set, the
                protocols are ignored and the "wrong" thing
                is done.  However, the IETF is moving toward
                changing this standard, so the behavior may
                become acceptable.  Please note that hosts
                downstream may still rewrite the address to
                be the true canonical name however.

      DontInitGroups
                [no short name] If set, sendmail will avoid
                using the initgroups(3) call.  If you are
                running NIS, this causes a sequential scan
                of the groups.byname map, which can cause
                your NIS server to be badly overloaded in a
                large domain.  The cost of this is that the
                only group found for users will be their
                primary group (the one in the password
                file), which will make file access
                permissions somewhat more restrictive.  Has
                no effect on systems that don't have group
                lists.











SMM:08-110         Sendmail Installation and Operation Guide


      DontProbeInterfaces
                [no short name] Sendmail normally finds the
                names of all interfaces active on your
                machine when it starts up and adds their
                name to the $=w class of known host aliases.
                If you have a large number of virtual
                interfaces or if your DNS inverse lookups
                are slow this can be time consuming.  This
                option turns off that probing.  However, you
                will need to be certain to include all
                variant names in the $=w class by some other
                mechanism.  If set to loopback, loopback
                interfaces (e.g., lo0) will not be probed.

      DontPruneRoutes
                [R] Normally, sendmail tries to eliminate
                any unnecessary explicit routes when sending
                an error message (as discussed in RFC 1123 S
                5.2.6).  For example, when sending an error
                message to

                    <@known1,@known2,@known3:user@unknown>

                sendmail will strip off the
                "@known1,@known2" in order to make the route
                as direct as possible.  However, if the R
                option is set, this will be disabled, and
                the mail will be sent to the first address
                in the route, even if later addresses are
                known.  This may be useful if you are caught
                behind a firewall.

      DoubleBounceAddress=error-address
                [no short name] If an error occurs when
                sending an error message, send the error
                report (termed a "double bounce" because it
                is an error "bounce" that occurs when trying
                to send another error "bounce") to the
                indicated address.  The address is macro
                expanded at the time of delivery.  If not
                set, defaults to "postmaster".  If set to an
                empty string, double bounces are dropped.

      EightBitMode=action
                [8] Set handling of eight-bit data.  There
                are two kinds of eight-bit data: that
                declared as such using the BODY=8BITMIME
                ESMTP declaration or the -B8BITMIME command
                line flag, and undeclared 8-bit data, that
                is, input that just happens to be eight
                bits.  There are three basic operations that
                can happen: undeclared 8-bit data can be
                automatically converted to 8BITMIME,










Sendmail Installation and Operation Guide         SMM:08-111


                undeclared 8-bit data can be passed as-is
                without conversion to MIME (``just send
                8''), and declared 8-bit data can be
                converted to 7-bits for transmission to a
                non-8BITMIME mailer.  The possible actions
                are:

                      s Reject undeclared 8-bit data (``strict'')
                      m Convert undeclared 8-bit data to MIME (``mime'')
                      p Pass undeclared 8-bit data (``pass'')

                In all cases properly declared 8BITMIME data
                will be converted to 7BIT as needed.  Note:
                if an automatic conversion is performed, a
                header with the following format will be
                added:

                    X-MIME-Autoconverted: from OLD to NEW by $j id $i

                where OLD and NEW describe the original
                format and the converted format,
                respectively.

      ErrorHeader=file-or-message
                [E] Prepend error messages with the
                indicated message.  If it begins with a
                slash, it is assumed to be the pathname of a
                file containing a message (this is the
                recommended setting).  Otherwise, it is a
                literal message.  The error file might
                contain the name, email address, and/or
                phone number of a local postmaster who could
                provide assistance to end users.  If the
                option is missing or null, or if it names a
                file which does not exist or which is not
                readable, no message is printed.

      ErrorMode=x
                [e] Dispose of errors using mode x.  The
                values for x are:

                    p   Print error messages (default)
                    q   No messages, just give exit status
                    m   Mail back errors
                    w   Write back errors (mail if user not logged in)
                    e   Mail back errors (when applicable) and give zero exit stat always

                Note that the last mode, "e", is for Berknet
                error processing and should not be used in
                normal circumstances.  Note, too, that mode
                "q", only applies to errors recognized
                before sendmail forks for background
                delivery.










SMM:08-112         Sendmail Installation and Operation Guide


      FallbackMXhost=fallbackhost
                [V] If specified, the fallbackhost acts like
                a very low priority MX on every host.  MX
                records will be looked up for this host,
                unless the name is surrounded by square
                brackets.  This is intended to be used by
                sites with poor network connectivity.
                Messages which are undeliverable due to
                temporary address failures (e.g., DNS
                failure) also go to the FallbackMXhost.

      FallBackSmartHost=hostname
                If specified, the FallBackSmartHost will be
                used in a last-ditch effort for each host.
                This is intended to be used by sites with
                "fake internal DNS", e.g., a company whose
                DNS accurately reflects the world inside
                that company's domain but not outside.

      FastSplit [no short name] If set to a value greater
                than zero (the default is one), it
                suppresses the MX lookups on addresses when
                they are initially sorted, i.e., for the
                first delivery attempt.  This usually
                results in faster envelope splitting unless
                the MX records are readily available in a
                local DNS cache.  To enforce initial sorting
                based on MX records set FastSplit to zero.
                If the mail is submitted directly from the
                command line, then the value also limits the
                number of processes to deliver the
                envelopes; if more envelopes are created
                they are only queued up and must be taken
                care of by a queue run.  Since the default
                submission method is via SMTP (either from a
                MUA or via the MSP), the value of FastSplit
                is seldom used to limit the number of
                processes to deliver the envelopes.

      ForkEachJob
                [Y] If set, deliver each job that is run
                from the queue in a separate process.

      ForwardPath=path
                [J] Set the path for searching for users'
                .forward files.  The default is
                "$z/.forward".  Some sites that use the
                automounter may prefer to change this to
                "/var/forward/$u" to search a file with the
                same name as the user in a system directory.
                It can also be set to a sequence of paths
                separated by colons; sendmail stops at the
                first file it can successfully and safely










Sendmail Installation and Operation Guide         SMM:08-113


                open.  For example,
                "/var/forward/$u:$z/.forward" will search
                first in /var/forward/username and then in
                ~username/.forward (but only if the first
                file does not exist).

      HeloName=name
                [no short name] Set the name to be used for
                HELO/EHLO (instead of $j).

      HelpFile=file
                [H] Specify the help file for SMTP.  If no
                file name is specified, "helpfile" is used.

      HoldExpensive
                [c] If an outgoing mailer is marked as being
                expensive, don't connect immediately.

      HostsFile=path
                [no short name] The path to the hosts
                database, normally "/etc/hosts".  This
                option is only consulted when sendmail is
                canonifying addresses, and then only when
                "files" is in the "hosts" service switch
                entry.  In particular, this file is never
                used when looking up host addresses; that is
                under the control of the system
                gethostbyname(3) routine.

      HostStatusDirectory=path
                [no short name] The location of the long
                term host status information.  When set,
                information about the status of hosts (e.g.,
                host down or not accepting connections) will
                be shared between all sendmail processes;
                normally, this information is only held
                within a single queue run.  This option
                requires a connection cache of at least 1 to
                function.  If the option begins with a
                leading `/', it is an absolute pathname;
                otherwise, it is relative to the mail queue
                directory.  A suggested value for sites
                desiring persistent host status is
                ".hoststat" (i.e., a subdirectory of the
                queue directory).

      IgnoreDots
                [i] Ignore dots in incoming messages.  This
                is always disabled (that is, dots are always
                accepted) when reading SMTP mail.

      InputMailFilters=name,name,...
                A comma separated list of filters which










SMM:08-114         Sendmail Installation and Operation Guide


                determines which filters (see the "X -- Mail
                Filter (Milter) Definitions" section) and
                the invocation sequence are contacted for
                incoming SMTP messages.  If none are set, no
                filters will be contacted.

      LDAPDefaultSpec=spec
                [no short name] Sets a default map
                specification for LDAP maps.  The value
                should only contain LDAP specific settings
                such as "-h host -p port -d bindDN".  The
                settings will be used for all LDAP maps
                unless the individual map specification
                overrides a setting.  This option should be
                set before any LDAP maps are defined.

      LogLevel=n
                [L] Set the log level to n.  Defaults to 9.

      Mxvalue   [no long version] Set the macro x to value.
                This is intended only for use from the
                command line.  The -M flag is preferred.

      MailboxDatabase
                [no short name] Type of lookup to find
                information about local mailboxes, defaults
                to ``pw'' which uses getpwnam.  Other types
                can be introduced by adding them to the
                source code, see libsm/mbdb.c for details.

      UseMSP    [no short name] Use as mail submission
                program, i.e., allow group writable queue
                files if the group is the same as that of a
                set-group-ID sendmail binary.  See the file
                sendmail/SECURITY in the distribution
                tarball.

      MatchGECOS
                [G] Allow fuzzy matching on the GECOS field.
                If this flag is set, and the usual user name
                lookups fail (that is, there is no alias
                with this name and a getpwnam fails),
                sequentially search the password file for a
                matching entry in the GECOS field.  This
                also requires that MATCHGECOS be turned on
                during compilation.  This option is not
                recommended.

      MaxAliasRecursion=N
                [no short name] The maximum depth of alias
                recursion (default: 10).












Sendmail Installation and Operation Guide         SMM:08-115


      MaxDaemonChildren=N
                [no short name] If set, sendmail will refuse
                connections when it has more than N children
                processing incoming mail or automatic queue
                runs.  This does not limit the number of
                outgoing connections.  If the default
                DeliveryMode (background) is used, then
                sendmail may create an almost unlimited
                number of children (depending on the number
                of transactions and the relative execution
                times of mail receiption and mail delivery).
                If the limit should be enforced, then a
                DeliveryMode other than background must be
                used.  If not set, there is no limit to the
                number of children -- that is, the system
                load average controls this.

      MaxHeadersLength=N
                [no short name] If set to a value greater
                than zero it specifies the maximum length of
                the sum of all headers.  This can be used to
                prevent a denial of service attack.  The
                default is 32K.

      MaxHopCount=N
                [h] The maximum hop count.  Messages that
                have been processed more than N times are
                assumed to be in a loop and are rejected.
                Defaults to 25.

      MaxMessageSize=N
                [no short name] Specify the maximum message
                size to be advertised in the ESMTP EHLO
                response.  Messages larger than this will be
                rejected.  If set to a value greater than
                zero, that value will be listed in the SIZE
                response, otherwise SIZE is advertised in
                the ESMTP EHLO response without a parameter.

      MaxMimeHeaderLength=N[/M]
                [no short name] Sets the maximum length of
                certain MIME header field values to N
                characters.  These MIME header fields are
                determined by being a member of class
                {checkMIMETextHeaders}, which currently
                contains only the header Content-
                Description.  For some of these headers
                which take parameters, the maximum length of
                each parameter is set to M if specified.  If
                /M is not specified, one half of N will be
                used.  By default, these values are 2048 and
                1024, respectively.  To allow any length, a
                value of 0 can be specified.










SMM:08-116         Sendmail Installation and Operation Guide


      MaxNOOPCommands=N
                Override the default of MAXNOOPCOMMANDS for
                the number of useless commands, see Section
                "Measures against Denial of Service
                Attacks".

      MaxQueueChildren=N
                [no short name] When set, this limits the
                number of concurrent queue runner processes
                to N.  This helps to control the amount of
                system resources used when processing the
                queue.  When there are multiple queue groups
                defined and the total number of queue
                runners for these queue groups would exceed
                MaxQueueChildren then the queue groups will
                not all run concurrently. That is, some
                portion of the queue groups will run
                concurrently such that MaxQueueChildren will
                not be exceeded, while the remaining queue
                groups will be run later (in round robin
                order). See also MaxRunnersPerQueue and the
                section Queue Group Declaration.  Notice:
                sendmail does not count individual queue
                runners, but only sets of processes that act
                on a workgroup.  Hence the actual number of
                queue runners may be lower than the limit
                imposed by MaxQueueChildren.  This
                discrepancy can be large if some queue
                runners have to wait for a slow server and
                if short intervals are used.

      MaxQueueRunSize=N
                [no short name] The maximum number of jobs
                that will be processed in a single queue
                run.  If not set, there is no limit on the
                size.  If you have very large queues or a
                very short queue run interval this could be
                unstable.  However, since the first N jobs
                in queue directory order are run (rather
                than the N highest priority jobs) this
                should be set as high as possible to avoid
                "losing" jobs that happen to fall late in
                the queue directory.  Note: this option also
                restricts the number of entries printed by
                mailq.  That is, if MaxQueueRunSize is set
                to a value N larger than zero, then only N
                entries are printed per queue group.

      MaxRecipientsPerMessage=N
                [no short name] The maximum number of
                recipients that will be accepted per message
                in an SMTP transaction.  Note: setting this
                too low can interfere with sending mail from










Sendmail Installation and Operation Guide         SMM:08-117


                MUAs that use SMTP for initial submission.
                If not set, there is no limit on the number
                of recipients per envelope.

      MaxRunnersPerQueue=N
                [no short name] This sets the default
                maximum number of queue runners for queue
                groups.  Up to N queue runners will work in
                parallel on a queue group's messages.  This
                is useful where the processing of a message
                in the queue might delay the processing of
                subsequent messages. Such a delay may be the
                result of non-erroneous situations such as a
                low bandwidth connection.  May be overridden
                on a per queue group basis by setting the
                Runners option; see the section Queue Group
                Declaration.  The default is 1 when not set.

      MeToo     [m] Send to me too, even if I am in an alias
                expansion.  This option is deprecated and
                will be removed from a future version.

      Milter    [no short name] This option has several
                sub(sub)options.  The names of the
                suboptions are separated by dots.  At the
                first level the following options are
                available:

                    LogLevel   Log level for input mail filter actions, defaults to LogLevel.
                    macros     Specifies list of macro to transmit to filters.
                               See list below.

                The ``macros'' option has the following
                suboptions which specify the list of macro
                to transmit to milters after a certain event
                occurred.

                    connect   After session connection start
                    helo      After EHLO/HELO command
                    envfrom   After MAIL From command
                    envrcpt   After RCPT To command
                    data      After DATA command.
                    eoh       After DATA command and header
                    eom       After DATA command and terminating ``.''

                By default the lists of macros are empty.
                Example:

                    O Milter.LogLevel=12
                    O Milter.macros.connect=j, _, {daemon_name}













SMM:08-118         Sendmail Installation and Operation Guide


      MinFreeBlocks=N
                [b] Insist on at least N blocks free on the
                filesystem that holds the queue files before
                accepting email via SMTP.  If there is
                insufficient space sendmail gives a 452
                response to the MAIL command.  This invites
                the sender to try again later.

      MaxQueueAge=age
                [no short name] If this is set to a value
                greater than zero, entries in the queue will
                be retried during a queue run only if the
                individual retry time has been reached which
                is doubled for each attempt.  The maximum
                retry time is limited by the specified
                value.

      MinQueueAge=age
                [no short name] Don't process any queued
                jobs that have been in the queue less than
                the indicated time interval.  This is
                intended to allow you to get responsiveness
                by processing the queue fairly frequently
                without thrashing your system by trying jobs
                too often.  The default units are minutes.
                Note: This option is ignored for queue runs
                that select a subset of the queue, i.e.,
                "-q[!][I|R|S|Q][string]"

      MustQuoteChars=s
                [no short name] Sets the list of characters
                that must be quoted if used in a full name
                that is in the phrase part of a ``phrase
                <address>'' syntax.  The default is ``'.''.
                The characters ``@,;:\()[]'' are always
                added to this list.  Note: To avoid
                potential breakage of DKIM signatures it is
                useful to set

                    O MustQuoteChars=.

                Moreover, relaxed header signing should be
                used for DKIM signatures.

      NiceQueueRun
                [no short name] The priority of queue
                runners (nice(3)).  This value must be
                greater or equal zero.

      NoRecipientAction
                [no short name] The action to take when you
                receive a message that has no valid
                recipient headers (To:, Cc:, Bcc:, or










Sendmail Installation and Operation Guide         SMM:08-119


                Apparently-To: -- the last included for back
                compatibility with old sendmails).  It can
                be None to pass the message on unmodified,
                which violates the protocol, Add-To to add a
                To: header with any recipients it can find
                in the envelope (which might expose Bcc:
                recipients), Add-Apparently-To to add an
                Apparently-To: header (this is only for
                back-compatibility and is officially
                deprecated), Add-To-Undisclosed to add a
                header "To: undisclosed-recipients:;" to
                make the header legal without disclosing
                anything, or Add-Bcc to add an empty Bcc:
                header.

      OldStyleHeaders
                [o] Assume that the headers may be in old
                format, i.e., spaces delimit names.  This
                actually turns on an adaptive algorithm: if
                any recipient address contains a comma,
                parenthesis, or angle bracket, it will be
                assumed that commas already exist.  If this
                flag is not on, only commas delimit names.
                Headers are always output with commas
                between the names.  Defaults to off.

      OperatorChars=charlist
                [$o macro] The list of characters that are
                considered to be "operators", that is,
                characters that delimit tokens.  All
                operator characters are tokens by
                themselves; sequences of non-operator
                characters are also tokens.  White space
                characters separate tokens but are not
                tokens themselves -- for example, "AAA.BBB"
                has three tokens, but "AAA BBB" has two.  If
                not set, OperatorChars defaults to ".:@[]";
                additionally, the characters "()<>,;" are
                always operators.  Note that OperatorChars
                must be set in the configuration file before
                any rulesets.

      PidFile=filename
                [no short name] Filename of the pid file.
                (default is _PATH_SENDMAILPID).  The
                filename is macro-expanded before it is
                opened, and unlinked when sendmail exits.

      PostmasterCopy=postmaster
                [P] If set, copies of error messages will be
                sent to the named postmaster.  Only the
                header of the failed message is sent.
                Errors resulting from messages with a










SMM:08-120         Sendmail Installation and Operation Guide


                negative precedence will not be sent.  Since
                most errors are user problems, this is
                probably not a good idea on large sites, and
                arguably contains all sorts of privacy
                violations, but it seems to be popular with
                certain operating systems vendors.  The
                address is macro expanded at the time of
                delivery.  Defaults to no postmaster copies.

      PrivacyOptions=opt,opt,...
                [p] Set the privacy options.  ``Privacy'' is
                really a misnomer; many of these are just a
                way of insisting on stricter adherence to
                the SMTP protocol.  The options can be
                selected from:

                    public              Allow open access
                    needmailhelo        Insist on HELO or EHLO command before MAIL
                    needexpnhelo        Insist on HELO or EHLO command before EXPN
                    noexpn              Disallow EXPN entirely, implies noverb.
                    needvrfyhelo        Insist on HELO or EHLO command before VRFY
                    novrfy              Disallow VRFY entirely
                    noetrn              Disallow ETRN entirely
                    noverb              Disallow VERB entirely
                    restrictmailq       Restrict mailq command
                    restrictqrun        Restrict -q command line flag
                    restrictexpand      Restrict -bv and -v command line flags
                    noreceipts          Don't return success DSNs[20]
                    nobodyreturn        Don't return the body of a message with DSNs
                    goaway              Disallow essentially all SMTP status queries
                    authwarnings        Put X-Authentication-Warning: headers in messages
                                        and log warnings
                    noactualrecipient   Don't put X-Actual-Recipient lines in DSNs
                                        which reveal the actual account that addresses map to.

                The "goaway" pseudo-flag sets all flags
                except "noreceipts", "restrictmailq",
                "restrictqrun", "restrictexpand", "noetrn",
                and "nobodyreturn".  If mailq is restricted,
                only people in the same group as the queue
                directory can print the queue.  If queue
                runs are restricted, only root and the owner
                of the queue directory can run the queue.
                The "restrictexpand" pseudo-flag instructs
                sendmail to drop privileges when the -bv
                option is given by users who are neither
                root nor the TrustedUser so users cannot
                read private aliases, forwards, or :include:
____________________
   [20]N.B.:  the  noreceipts flag turns off support for RFC
1891 (Delivery Status Notification).












Sendmail Installation and Operation Guide         SMM:08-121


                files.  It will add the "NonRootSafeAddr" to
                the "DontBlameSendmail" option to prevent
                misleading unsafe address warnings.  It also
                overrides the -v (verbose) command line
                option to prevent information leakage.
                Authentication Warnings add warnings about
                various conditions that may indicate
                attempts to spoof the mail system, such as
                using a non-standard queue directory.

      ProcessTitlePrefix=string
                [no short name] Prefix the process title
                shown on 'ps' listings with string.  The
                string will be macro processed.

      QueueDirectory=dir
                [Q] The QueueDirectory option serves two
                purposes.  First, it specifies the directory
                or set of directories that comprise the
                default queue group.  Second, it specifies
                the directory D which is the ancestor of all
                queue directories, and which sendmail uses
                as its current working directory.  When
                sendmail dumps core, it leaves its core
                files in D.  There are two cases.  If dir
                ends with an asterisk (eg,
                /var/spool/mqueue/qd*), then all of the
                directories or symbolic links to directories
                beginning with `qd' in /var/spool/mqueue
                will be used as queue directories of the
                default queue group, and /var/spool/mqueue
                will be used as the working directory D.
                Otherwise, dir must name a directory
                (usually /var/spool/mqueue): the default
                queue group consists of the single queue
                directory dir, and the working directory D
                is set to dir.  To define additional groups
                of queue directories, use the configuration
                file `Q' command.  Do not change the queue
                directory structure while sendmail is
                running.

      QueueFactor=factor
                [q] Use factor as the multiplier in the map
                function to decide when to just queue up
                jobs rather than run them.  This value is
                divided by the difference between the
                current load average and the load average
                limit (QueueLA option) to determine the
                maximum message priority that will be sent.
                Defaults to 600000.












SMM:08-122         Sendmail Installation and Operation Guide


      QueueLA=LA
                [x] When the system load average exceeds LA
                and the QueueFactor (q) option divided by
                the difference in the current load average
                and the QueueLA option plus one is less than
                the priority of the message, just queue
                messages (i.e., don't try to send them).
                Defaults to 8 multiplied by the number of
                processors online on the system (if that can
                be determined).

      QueueFileMode=mode
                [no short name] Default permissions for
                queue files (octal).  If not set, sendmail
                uses 0600 unless its real and effective uid
                are different in which case it uses 0644.

      QueueSortOrder=algorithm
                [no short name] Sets the algorithm used for
                sorting the queue.  Only the first character
                of the value is used.  Legal values are
                "host" (to order by the name of the first
                host name of the first recipient),
                "filename" (to order by the name of the
                queue file name), "time" (to order by the
                submission/creation time), "random" (to
                order randomly), "modification" (to order by
                the modification time of the qf file (older
                entries first)), "none" (to not order), and
                "priority" (to order by message priority).
                Host ordering makes better use of the
                connection cache, but may tend to process
                low priority messages that go to a single
                host over high priority messages that go to
                several hosts; it probably shouldn't be used
                on slow network links.  Filename and
                modification time ordering saves the
                overhead of reading all of the queued items
                before starting the queue run.  Creation
                (submission) time ordering is almost always
                a bad idea, since it allows large, bulk mail
                to go out before smaller, personal mail, but
                may have applicability on some hosts with
                very fast connections.  Random is useful if
                several queue runners are started by hand
                which try to drain the same queue since odds
                are they will be working on different parts
                of the queue at the same time.  Priority
                ordering is the default.

      QueueTimeout=timeout
                [T] A synonym for "Timeout.queuereturn".
                Use that form instead of the "QueueTimeout"










Sendmail Installation and Operation Guide         SMM:08-123


                form.

      RandFile  [no short name] Name of file containing
                random data or the name of the UNIX socket
                if EGD is used.  A (required) prefix "egd:"
                or "file:" specifies the type.  STARTTLS
                requires this filename if the compile flag
                HASURANDOMDEV is not set (see
                sendmail/README).

      ResolverOptions=options
                [I] Set resolver options.  Values can be set
                using +flag and cleared using -flag; the
                flags can be "debug", "aaonly", "usevc",
                "primary", "igntc", "recurse", "defnames",
                "stayopen", "use_inet6", or "dnsrch".  The
                string "HasWildcardMX" (without a + or -)
                can be specified to turn off matching
                against MX records when doing name
                canonifications.  The string
                "WorkAroundBrokenAAAA" (without a + or -)
                can be specified to work around some broken
                nameservers which return SERVFAIL (a
                temporary failure) on T_AAAA (IPv6) lookups.
                Notice: it might be necessary to apply the
                same (or similar) options to submit.cf too.

      RequiresDirfsync
                [no short name] This option can be used to
                override the compile time flag
                REQUIRES_DIR_FSYNC at runtime by setting it
                to false.  If the compile time flag is not
                set, the option is ignored.  The flag turns
                on support for file systems that require to
                call fsync() for a directory if the meta-
                data in it has been changed.  This should be
                turned on at least for older versions of
                ReiserFS; it is enabled by default for
                Linux.  According to some information this
                flag is not needed anymore for kernel 2.4.16
                and newer.

      RrtImpliesDsn
                [R] If this option is set, a "Return-
                Receipt-To:" header causes the request of a
                DSN, which is sent to the envelope sender as
                required by RFC 1891, not to the address
                given in the header.

      RunAsUser=user
                [no short name] The user parameter may be a
                user name (looked up in /etc/passwd) or a
                numeric user id; either form can have










SMM:08-124         Sendmail Installation and Operation Guide


                ":group" attached (where group can be
                numeric or symbolic).  If set to a non-zero
                (non-root) value, sendmail will change to
                this user id shortly after startup[21].
                This avoids a certain class of security
                problems.  However, this means that all
                ".forward" and ":include:" files must be
                readable by the indicated user and all files
                to be written must be writable by user Also,
                all file and program deliveries will be
                marked unsafe unless the option
                DontBlameSendmail=NonRootSafeAddr is set, in
                which case the delivery will be done as
                user.  It is also incompatible with the
                SafeFileEnvironment option.  In other words,
                it may not actually add much to security on
                an average system, and may in fact detract
                from security (because other file
                permissions must be loosened).  However, it
                should be useful on firewalls and other
                places where users don't have accounts and
                the aliases file is well constrained.

      RecipientFactor=fact
                [y] The indicated factor is added to the
                priority (thus lowering the priority of the
                job) for each recipient, i.e., this value
                penalizes jobs with large numbers of
                recipients.  Defaults to 30000.

      RefuseLA=LA
                [X] When the system load average exceeds LA,
                refuse incoming SMTP connections.  Defaults
                to 12 multiplied by the number of processors
                online on the system (if that can be
                determined).

      RejectLogInterval=timeout
                [no short name] Log interval when refusing
                connections for this long (default: 3h).

      RetryFactor=fact
                [Z] The factor is added to the priority
                every time a job is processed.  Thus, each
                time a job is processed, its priority will
                be decreased by the indicated value.  In
                most environments this should be positive,
____________________
   [21]When  running  as  a  daemon, it changes to this user
after accepting a connection but  before  reading  any  SMTP
commands.












Sendmail Installation and Operation Guide         SMM:08-125


                since hosts that are down are all too often
                down for a long time.  Defaults to 90000.

      SafeFileEnvironment=dir
                [no short name] If this option is set,
                sendmail will do a chroot(2) call into the
                indicated directory before doing any file
                writes.  If the file name specified by the
                user begins with dir, that partial path name
                will be stripped off before writing, so (for
                example) if the SafeFileEnvironment variable
                is set to "/safe" then aliases of
                "/safe/logs/file" and "/logs/file" actually
                indicate the same file.  Additionally, if
                this option is set, sendmail refuses to
                deliver to symbolic links.

      SaveFromLine
                [f] Save UNIX-style "From" lines at the
                front of headers.  Normally they are assumed
                redundant and discarded.

      SendMimeErrors
                [j] If set, send error messages in MIME
                format (see RFC 2045 and RFC 1344 for
                details).  If disabled, sendmail will not
                return the DSN keyword in response to an
                EHLO and will not do Delivery Status
                Notification processing as described in RFC
                1891.

      ServerCertFile
                [no short name] File containing the
                certificate of the server, i.e., this
                certificate is used when sendmail acts as
                server (used for STARTTLS).

      ServerKeyFile
                [no short name] File containing the private
                key belonging to the server certificate
                (used for STARTTLS).

      ServerSSLOptions
                A space or comma separated list of SSL
                related options for the server side.  See
                SSL_CTX_set_options(3) for a list; the
                available values depend on the OpenSSL
                version against which sendmail is compiled.
                By default, SSL_OP_ALL
                -SSL_OP_TLSEXT_PADDING are used (if those
                options are available).  Options can be
                cleared by preceding them with a minus sign.
                It is also possible to specify numerical










SMM:08-126         Sendmail Installation and Operation Guide


                values, e.g., -0x0010.

      ServiceSwitchFile=filename
                [no short name] If your host operating
                system has a service switch abstraction
                (e.g., /etc/nsswitch.conf on Solaris or
                /etc/svc.conf on Ultrix and DEC OSF/1) that
                service will be consulted and this option is
                ignored.  Otherwise, this is the name of a
                file that provides the list of methods used
                to implement particular services.  The
                syntax is a series of lines, each of which
                is a sequence of words.  The first word is
                the service name, and following words are
                service types.  The services that sendmail
                consults directly are "aliases" and "hosts."
                Service types can be "dns", "nis",
                "nisplus", or "files" (with the caveat that
                the appropriate support must be compiled in
                before the service can be referenced).  If
                ServiceSwitchFile is not specified, it
                defaults to /etc/mail/service.switch.  If
                that file does not exist, the default switch
                is:

                    aliases             files
                    hosts               dns nis files

                The default file is
                "/etc/mail/service.switch".

      SevenBitInput
                [7] Strip input to seven bits for
                compatibility with old systems.  This
                shouldn't be necessary.

      SharedMemoryKey
                [no short name] Key to use for shared memory
                segment; if not set (or 0), shared memory
                will not be used.  If set to -1 sendmail can
                select a key itself provided that also
                SharedMemoryKeyFile is set.  Requires
                support for shared memory to be compiled
                into sendmail.  If this option is set,
                sendmail can share some data between
                different instances.  For example, the
                number of entries in a queue directory or
                the available space in a file system.  This
                allows for more efficient program execution,
                since only one process needs to update the
                data instead of each individual process
                gathering the data each time it is required.











Sendmail Installation and Operation Guide         SMM:08-127


      SharedMemoryKeyFile
                [no short name] If SharedMemoryKey is set to
                -1 then the automatically selected shared
                memory key will be stored in the specified
                file.

      SingleLineFromHeader
                [no short name] If set, From: lines that
                have embedded newlines are unwrapped onto
                one line.  This is to get around a botch in
                Lotus Notes that apparently cannot
                understand legally wrapped RFC 822 headers.

      SingleThreadDelivery
                [no short name] If set, a client machine
                will never try to open two SMTP connections
                to a single server machine at the same time,
                even in different processes.  That is, if
                another sendmail is already talking to some
                host a new sendmail will not open another
                connection.  This property is of mixed
                value; although this reduces the load on the
                other machine, it can cause mail to be
                delayed (for example, if one sendmail is
                delivering a huge message, other sendmails
                won't be able to send even small messages).
                Also, it requires another file descriptor
                (for the lock file) per connection, so you
                may have to reduce the ConnectionCacheSize
                option to avoid running out of per-process
                file descriptors.  Requires the
                HostStatusDirectory option.

      SmtpGreetingMessage=message
                [$e macro] The message printed when the SMTP
                server starts up.  Defaults to "$j Sendmail
                $v ready at $b".

      SoftBounce
                If set, issue temporary errors (4xy) instead
                of permanent errors (5xy).  This can be
                useful during testing of a new configuration
                to avoid erroneous bouncing of mails.

      SSLEngine Name of SSL engine to use.  The available
                values depend on the OpenSSL version against
                which sendmail is compiled, see

                    openssl engine -v

                for some information.












SMM:08-128         Sendmail Installation and Operation Guide


      SSLEnginePath
                Path to dynamic library for SSL engine.
                This option is only useful if SSLEngine is
                set.  If both are set, the engine will be
                loaded dynamically at runtime using the
                concatenation of the path, a slash "/", the
                string "lib", the value of SSLEngine, and
                the string ".so".  If only SSLEngine is set
                then the static version of the engine is
                used.

      StatusFile=file
                [S] Log summary statistics in the named
                file.  If no file name is specified,
                "statistics" is used.  If not set, no
                summary statistics are saved.  This file
                does not grow in size.  It can be printed
                using the mailstats(8) program.

      SuperSafe [s] This option can be set to True, False,
                Interactive, or PostMilter.  If set to True,
                sendmail will be super-safe when running
                things, i.e., always instantiate the queue
                file, even if you are going to attempt
                immediate delivery.  Sendmail always
                instantiates the queue file before returning
                control to the client under any
                circumstances.  This should really always be
                set to True.  The Interactive value has been
                introduced in 8.12 and can be used together
                with DeliveryMode=i.  It skips some
                synchronization calls which are effectively
                doubled in the code execution path for this
                mode.  If set to PostMilter, sendmail defers
                synchronizing the queue file until any
                milters have signaled acceptance of the
                message.  PostMilter is useful only when
                sendmail is running as an SMTP server; in
                all other situations it acts the same as
                True.

      TLSFallbacktoClear
                [no short name] If set, sendmail immediately
                tries an outbound connection again without
                STARTTLS after a TLS handshake failure.
                Note: this applies to all connections even
                if TLS specific requirements are set (see
                rulesets tls_rcpt and tls_client ).  Hence
                such requirements will cause an error on a
                retry without STARTTLS.  Therefore they
                should only trigger a temporary failure so
                the connection is later on tried again.











Sendmail Installation and Operation Guide         SMM:08-129


      TLSSrvOptions
                [no short name] List of options for SMTP
                STARTTLS for the server consisting of single
                characters with intervening white space or
                commas.  The flag ``V'' disables client
                verification, and hence it is not possible
                to use a client certificate for relaying.
                The flag ``C'' removes the requirement for
                the TLS server to have a cert.  This only
                works under very specific circumstances and
                should only be used if the consequences are
                understood, e.g., clients may not work with
                a server using this.

      TempFileMode=mode
                [F] The file mode for transcript files,
                files to which sendmail delivers directly,
                files in the HostStatusDirectory, and
                StatusFile.  It is interpreted in octal by
                default.  Defaults to 0600.

      Timeout.type=timeout
                [r; subsumes old T option as well] Set
                timeout values.  For more information, see
                section 4.1.

      TimeZoneSpec=tzinfo
                [t] Set the local time zone info to tzinfo
                -- for example, "PST8PDT".  Actually, if
                this is not set, the TZ environment variable
                is cleared (so the system default is used);
                if set but null, the user's TZ variable is
                used, and if set and non-null the TZ
                variable is set to this value.

      TrustedUser=user
                [no short name] The user parameter may be a
                user name (looked up in /etc/passwd) or a
                numeric user id.  Trusted user for file
                ownership and starting the daemon.  If set,
                generated alias databases and the control
                socket (if configured) will automatically be
                owned by this user.

      TryNullMXList
                [w] If this system is the "best" (that is,
                lowest preference) MX for a given host, its
                configuration rules should normally detect
                this situation and treat that condition
                specially by forwarding the mail to a UUCP
                feed, treating it as local, or whatever.
                However, in some cases (such as Internet
                firewalls) you may want to try to connect










SMM:08-130         Sendmail Installation and Operation Guide


                directly to that host as though it had no MX
                records at all.  Setting this option causes
                sendmail to try this.  The downside is that
                errors in your configuration are likely to
                be diagnosed as "host unknown" or "message
                timed out" instead of something more
                meaningful.  This option is disrecommended.

      UnixFromLine=fromline
                [$l macro] Defines the format used when
                sendmail must add a UNIX-style From_ line
                (that is, a line beginning
                "From<space>user").  Defaults to "From $g
                $d".  Don't change this unless your system
                uses a different UNIX mailbox format (very
                unlikely).

      UnsafeGroupWrites
                [no short name] If set (default), :include:
                and .forward files that are group writable
                are considered "unsafe", that is, they
                cannot reference programs or write directly
                to files.  World writable :include: and
                .forward files are always unsafe.  Note: use
                DontBlameSendmail instead; this option is
                deprecated.

      UseCompressedIPv6Addresses
                [no short name] If set, the compressed
                format of IPv6 addresses, such as IPV6:::1,
                will be used, instead of the uncompressed
                format, such as IPv6:0:0:0:0:0:0:0:1.

      UseErrorsTo
                [l] If there is an "Errors-To:" header, send
                error messages to the addresses listed
                there.  They normally go to the envelope
                sender.  Use of this option causes sendmail
                to violate RFC 1123.  This option is
                disrecommended and deprecated.

      UserDatabaseSpec=udbspec
                [U] The user database specification.

      Verbose   [v] Run in verbose mode.  If this is set,
                sendmail adjusts options HoldExpensive (old
                c) and DeliveryMode (old d) so that all mail
                is delivered completely in a single job so
                that you can see the entire delivery
                process.  Option Verbose should never be set
                in the configuration file; it is intended
                for command line use only.  Note that the
                use of option Verbose can cause










Sendmail Installation and Operation Guide         SMM:08-131


                authentication information to leak, if you
                use a sendmail client to authenticate to a
                server.  If the authentication mechanism
                uses plain text passwords (as with LOGIN or
                PLAIN), then the password could be
                compromised.  To avoid this, do not install
                sendmail set-user-ID root, and disable the
                VERB SMTP command with a suitable
                PrivacyOptions setting.

      XscriptFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before a memory-based queue transcript file
                becomes disk-based.  The default is 4096
                bytes.

      All options can be specified on the command line using
      the -O or -o flag, but most will cause sendmail to
      relinquish its set-user-ID permissions.  The options
      that will not cause this are SevenBitInput [7],
      EightBitMode [8], MinFreeBlocks [b],
      CheckpointInterval [C], DeliveryMode [d], ErrorMode
      [e], IgnoreDots [i], SendMimeErrors [j], LogLevel [L],
      MeToo [m], OldStyleHeaders [o], PrivacyOptions [p],
      SuperSafe [s], Verbose [v], QueueSortOrder,
      MinQueueAge, DefaultCharSet, Dial Delay,
      NoRecipientAction, ColonOkInAddr, MaxQueueRunSize,
      SingleLineFromHeader, and AllowBogusHELO.  Actually,
      PrivacyOptions [p] given on the command line are added
      to those already specified in the sendmail.cf file,
      i.e., they can't be reset.  Also, M (define macro)
      when defining the r or s macros is also considered
      "safe".

   5.7.  P -- Precedence Definitions

           Values for the "Precedence:" field may be defined
      using the P control line.  The syntax of this field
      is:

          Pname=num

      When the name is found in a "Precedence:" field, the
      message class is set to num.  Higher numbers mean
      higher precedence.  Numbers less than zero have the
      special property that if an error occurs during
      processing the body of the message will not be
      returned; this is expected to be used for "bulk" mail
      such as through mailing lists.  The default precedence
      is zero.  For example, our list of precedences is:













SMM:08-132         Sendmail Installation and Operation Guide


          Pfirst-class=0
          Pspecial-delivery=100
          Plist=-30
          Pbulk=-60
          Pjunk=-100

      People writing mailing list exploders are encouraged
      to use "Precedence: list".  Older versions of sendmail
      (which discarded all error returns for negative
      precedences) didn't recognize this name, giving it a
      default precedence of zero.  This allows list
      maintainers to see error returns on both old and new
      versions of sendmail.

   5.8.  V -- Configuration Version Level

           To provide compatibility with old configuration
      files, the V line has been added to define some very
      basic semantics of the configuration file.  These are
      not intended to be long term supports; rather, they
      describe compatibility features which will probably be
      removed in future releases.

           N.B.: these version levels have nothing to do
      with the version number on the files.  For example, as
      of this writing version 10 config files (specifically,
      8.10) used version level 9 configurations.

           "Old" configuration files are defined as version
      level one.  Version level two files make the following
      changes:

       (1)   Host name canonification ($[ ... $]) appends a
             dot if the name is recognized; this gives the
             config file a way of finding out if anything
             matched.  (Actually, this just initializes the
             "host" map with the "-a."  flag -- you can
             reset it to anything you prefer by declaring
             the map explicitly.)

       (2)   Default host name extension is consistent
             throughout processing; version level one
             configurations turned off domain extension
             (that is, adding the local domain name) during
             certain points in processing.  Version level
             two configurations are expected to include a
             trailing dot to indicate that the name is
             already canonical.

       (3)   Local names that are not aliases are passed
             through a new distinguished ruleset five; this
             can be used to append a local relay.  This
             behavior can be prevented by resolving the










Sendmail Installation and Operation Guide         SMM:08-133


             local name with an initial `@'.  That is,
             something that resolves to a local mailer and a
             user name of "vikki" will be passed through
             ruleset five, but a user name of "@vikki" will
             have the `@' stripped, will not be passed
             through ruleset five, but will otherwise be
             treated the same as the prior example.  The
             expectation is that this might be used to
             implement a policy where mail sent to "vikki"
             was handled by a central hub, but mail sent to
             "vikki@localhost" was delivered directly.

           Version level three files allow # initiated
      comments on all lines.  Exceptions are backslash
      escaped # marks and the $# syntax.

           Version level four configurations are completely
      equivalent to level three for historical reasons.

           Version level five configuration files change the
      default definition of $w to be just the first
      component of the hostname.

           Version level six configuration files change many
      of the local processing options (such as aliasing and
      matching the beginning of the address for `|'
      characters) to be mailer flags; this allows fine-
      grained control over the special local processing.
      Level six configuration files may also use long option
      names.  The ColonOkInAddr option (to allow colons in
      the local-part of addresses) defaults on for lower
      numbered configuration files; the configuration file
      requires some additional intelligence to properly
      handle the RFC 822 group construct.

           Version level seven configuration files used new
      option names to replace old macros ($e became
      SmtpGreetingMessage, $l became UnixFromLine, and $o
      became OperatorChars.  Also, prior to version seven,
      the F=q flag (use 250 instead of 252 return value for
      SMTP VRFY commands) was assumed.

           Version level eight configuration files allow $#
      on the left hand side of ruleset lines.

           Version level nine configuration files allow
      parentheses in rulesets, i.e. they are not treated as
      comments and hence removed.

           Version level ten configuration files allow queue
      group definitions.












SMM:08-134         Sendmail Installation and Operation Guide


           The V line may have an optional /vendor to
      indicate that this configuration file uses
      modifications specific to a particular vendor[22].
      You may use "/Berkeley" to emphasize that this
      configuration file uses the Berkeley dialect of
      sendmail.

   5.9.  K -- Key File Declaration

           Special maps can be defined using the line:

          Kmapname mapclass arguments

      The mapname is the handle by which this map is
      referenced in the rewriting rules.  The mapclass is
      the name of a type of map; these are compiled in to
      sendmail.  The arguments are interpreted depending on
      the class; typically, there would be a single argument
      naming the file containing the map.

           Maps are referenced using the syntax:

          $( map key $@ arguments $: default $)

      where either or both of the arguments or default
      portion may be omitted.  The $@ arguments may appear
      more than once.  The indicated key and arguments are
      passed to the appropriate mapping function.  If it
      returns a value, it replaces the input.  If it does
      not return a value and the default is specified, the
      default replaces the input.  Otherwise, the input is
      unchanged.

           The arguments are passed to the map for arbitrary
      use.  Most map classes can interpolate these arguments
      into their values using the syntax "%n" (where n is a
      digit) to indicate the corresponding argument.
      Argument "%0" indicates the database key.  For
      example, the rule

          R$- ! $+       $: $(uucp $1 $@ $2 $: $2 @ $1 . UUCP $)

      Looks up the UUCP name in a (user defined) UUCP map;
      if not found it turns it into ".UUCP" form.  The
      database might contain records like:

____________________
   [22]And  of  course,  vendors  are  encouraged   to   add
themselves  to the list of recognized vendors by editing the
routine  setvendor  in  conf.c.   Please  send   e-mail   to
sendmail@Sendmail.ORG to register your vendor dialect.












Sendmail Installation and Operation Guide         SMM:08-135


          decvax         %1@%0.DEC.COM
          research       %1@%0.ATT.COM

      Note that default clauses never do this mapping.

           The built-in map with both name and class "host"
      is the host name canonicalization lookup.  Thus, the
      syntax:

          $(host hostname$)

      is equivalent to:

          $[hostname$]


           There are many defined classes.

      cdb       Database lookups using the cdb(3) library.
                Sendmail must be compiled with CDB defined.

      dbm       Database lookups using the ndbm(3) library.
                Sendmail must be compiled with NDBM defined.

      btree     Database lookups using the btree interface
                to the Berkeley DB library.  Sendmail must
                be compiled with NEWDB defined.

      hash      Database lookups using the hash interface to
                the Berkeley DB library.  Sendmail must be
                compiled with NEWDB defined.

      nis       NIS lookups.  Sendmail must be compiled with
                NIS defined.

      nisplus   NIS+ lookups.  Sendmail must be compiled
                with NISPLUS defined.  The argument is the
                name of the table to use for lookups, and
                the -k and -v flags may be used to set the
                key and value columns respectively.

      hesiod    Hesiod lookups.  Sendmail must be compiled
                with HESIOD defined.

      ldap      LDAP X500 directory lookups.  Sendmail must
                be compiled with LDAPMAP defined.  The map
                supports most of the standard arguments and
                most of the command line arguments of the
                ldapsearch program.  Note that, by default,
                if a single query matches multiple values,
                only the first value will be returned unless
                the -z (value separator) map option is set.
                Also, the -1 map flag will treat a multiple










SMM:08-136         Sendmail Installation and Operation Guide


                value return as if there were no matches.

      netinfo   NeXT NetInfo lookups.  Sendmail must be
                compiled with NETINFO defined.

      text      Text file lookups.  The format of the text
                file is defined by the -k (key field
                number), -v (value field number), and -z
                (field delimiter) options.

      ph        PH query map.  Contributed and supported by
                Mark Roth, roth@uiuc.edu.

      nsd       nsd map for IRIX 6.5 and later.  Contributed
                and supported by Bob Mende of SGI,
                mende@sgi.com.

      stab      Internal symbol table lookups.  Used
                internally for aliasing.

      implicit  Sequentially try a list of available map
                types: hash, dbm, and cdb.  It is the
                default for alias files if no class is
                specified.  If is no matching map type is
                found, the text version is used for the
                alias file, but other maps fail to open.

      user      Looks up users using getpwnam(3).  The -v
                flag can be used to specify the name of the
                field to return (although this is normally
                used only to check the existence of a user).

      host      Canonifies host domain names.  Given a host
                name it calls the name server to find the
                canonical name for that host.

      bestmx    Returns the best MX record for a host name
                given as the key.  The current machine is
                always preferred -- that is, if the current
                machine is one of the hosts listed as a
                lowest-preference MX record, then it will be
                guaranteed to be returned.  This can be used
                to find out if this machine is the target
                for an MX record, and mail can be accepted
                on that basis.  If the -z option is given,
                then all MX names are returned, separated by
                the given delimiter.  Note: the return value
                is deterministic, i.e., even if multiple MX
                records have the same preference, they will
                be returned in the same order.

      dns       This map requires the option -R to specify
                the DNS resource record type to lookup.  The










Sendmail Installation and Operation Guide         SMM:08-137


                following types are supported: A, AAAA,
                AFSDB, CNAME, MX, NS, PTR, SRV, and TXT.  A
                map lookup will return only one record
                unless the -z (value separator) option is
                set.  Hence for some types, e.g., MX
                records, the return value might be a random
                element of the results due to randomizing in
                the DNS resolver, if only one element is
                returned.

      arpa      Returns the ``reverse'' for the given IP
                (IPv4 or IPv6) address, i.e., the string for
                the PTR lookup, but without trailing
                ip6.arpa or in-addr.arpa.  For example, the
                following configuration lines:

                    Karpa arpa
                    SArpa
                    R$+            $: $(arpa $1 $)

                work like this in test mode:

                    sendmail -bt
                    ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
                    Enter <ruleset> <address>
                    > Arpa IPv6:1:2:dead:beef:9876:0:0:1
                    Arpa               input: IPv6 : 1 : 2 : dead : beef : 9876 : 0 : 0 : 1
                    Arpa             returns: 1 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 6 . 7 . 8 . 9 . f . e . e . b . d . a . e . d . 2 . 0 . 0 . 0 . 1 . 0 . 0 . 0
                    > Arpa 1.2.3.4
                    Arpa               input: 1 . 2 . 3 . 4
                    Arpa             returns: 4 . 3 . 2 . 1


      sequence  The arguments on the `K' line are a list of
                maps; the resulting map searches the
                argument maps in order until it finds a
                match for the indicated key.  For example,
                if the key definition is:

                    Kmap1 ...
                    Kmap2 ...
                    Kseqmap sequence map1 map2

                then a lookup against "seqmap" first does a
                lookup in map1.  If that is found, it
                returns immediately.  Otherwise, the same
                key is used for map2.

      syslog    the key is logged via syslogd(8).  The
                lookup returns the empty string.

      switch    Much like the "sequence" map except that the
                order of maps is determined by the service










SMM:08-138         Sendmail Installation and Operation Guide


                switch.  The argument is the name of the
                service to be looked up; the values from the
                service switch are appended to the map name
                to create new map names.  For example,
                consider the key definition:

                    Kali switch aliases

                together with the service switch entry:

                    aliases        nis files

                This causes a query against the map "ali" to
                search maps named "ali.nis" and "ali.files"
                in that order.

      dequote   Strip double quotes (") from a name.  It
                does not strip backslashes, and will not
                strip quotes if the resulting string would
                contain unscannable syntax (that is, basic
                errors like unbalanced angle brackets; more
                sophisticated errors such as unknown hosts
                are not checked).  The intent is for use
                when trying to accept mail from systems such
                as DECnet that routinely quote odd syntax
                such as

                    "49ers::ubell"

                A typical usage is probably something like:

                    Kdequote dequote

                    ...

                    R$-            $: $(dequote $1 $)
                    R$- $+         $: $>3 $1 $2

                Care must be taken to prevent unexpected
                results; for example,

                    "|someprogram < input > output"

                will have quotes stripped, but the result is
                probably not what you had in mind.
                Fortunately these cases are rare.

      regex     The map definition on the K line contains a
                regular expression.  Any key input is
                compared to that expression using the POSIX
                regular expressions routines regcomp(),
                regerr(), and regexec().  Refer to the
                documentation for those routines for more










Sendmail Installation and Operation Guide         SMM:08-139


                information about the regular expression
                matching.  No rewriting of the key is done
                if the -m flag is used.  Without it, the key
                is discarded or if -s if used, it is
                substituted by the substring matches,
                delimited by $| or the string specified with
                the the -d option.  The options available
                for the map are

                    -n  not
                    -f  case sensitive
                    -b  basic regular expressions (default is extended)
                    -s  substring match
                    -d  set the delimiter string used for -s
                    -a  append string to key
                    -m  match only, do not replace/discard value
                    -D  perform no lookup in deferred delivery mode.

                The -s option can include an optional
                parameter which can be used to select the
                substrings in the result of the lookup.  For
                example,

                    -s1,3,4

                The delimiter string specified via the -d
                option is the sequence of characters after d
                ending at the first space.  Hence it isn't
                possible to specify a space as delimiter, so
                if the option is immediately followed by a
                space the delimiter string is empty, which
                means the substrings are joined.

                Notes: to match a $ in a string, \$$ must be
                used.  If the pattern contains spaces, they
                must be replaced with the blank substitution
                character, unless it is space itself.

      program   The arguments on the K line are the pathname
                to a program and any initial parameters to
                be passed.  When the map is called, the key
                is added to the initial parameters and the
                program is invoked as the default user/group
                id.  The first line of standard output is
                returned as the value of the lookup.  This
                has many potential security problems, and
                has terrible performance; it should be used
                only when absolutely necessary.

      macro     Set or clear a macro value.  To set a macro,
                pass the value as the first argument in the
                map lookup.  To clear a macro, do not pass
                an argument in the map lookup.  The map










SMM:08-140         Sendmail Installation and Operation Guide


                always returns the empty string.  Example of
                typical usage include:

                    Kstorage macro

                    ...

                    # set macro ${MyMacro} to the ruleset match
                    R$+ $: $(storage {MyMacro} $@ $1 $) $1
                    # set macro ${MyMacro} to an empty string
                    R$* $: $(storage {MyMacro} $@ $) $1
                    # clear macro ${MyMacro}
                    R$- $: $(storage {MyMacro} $) $1


      arith     Perform simple arithmetic operations.  The
                operation is given as key, currently +, -,
                *, /, %, |, & (bitwise OR, AND), l (for less
                than), =, and r (for random) are supported.
                The two operands are given as arguments.
                The lookup returns the result of the
                computation, i.e., TRUE or FALSE for
                comparisons, integer values otherwise.  The
                r operator returns a pseudo-random number
                whose value lies between the first and
                second operand (which requires that the
                first operand is smaller than the second).
                All options which are possible for maps are
                ignored.  A simple example is:

                    Kcomp arith

                    ...

                    Scheck_etrn
                    R$* $: $(comp l $@ $&{load_avg} $@ 7 $) $1
                    RFALSE$# error ...


      socket    The socket map uses a simple request/reply
                protocol over TCP or UNIX domain sockets to
                query an external server.  Both requests and
                replies are text based and encoded as
                netstrings, i.e., a string "hello there"
                becomes:

                    11:hello there,

                Note: neither requests nor replies end with
                CRLF.

                The request consists of the database map
                name and the lookup key separated by a space










Sendmail Installation and Operation Guide         SMM:08-141


                character:


                    <mapname> ' ' <key>


                The server responds with a status indicator
                and the result (if any):


                    <status> ' ' <result>


                The status indicator specifies the result of
                the lookup operation itself and is one of
                the following upper case words:

                    OK       the key was found, result contains the looked up value
                    NOTFOUND the key was not found, the result is empty
                    TEMP     a temporary failure occurred
                    TIMEOUT  a timeout occurred on the server side
                    PERM     a permanent failure occurred


                In case of errors (status TEMP, TIMEOUT or
                PERM) the result field may contain an
                explanatory message.  However, the
                explanatory message is not used any further
                by sendmail.

                Example replies:

                    31:OK resolved.address@example.com,



                    56:OK error:550 5.7.1 User does not accept mail from sender,


                in case of successful lookups, or:

                    8:NOTFOUND,


                in case the key was not found, or:

                    55:TEMP this text explains that we had a temporary failure,


                in case of a temporary map lookup failure.

                The socket map uses the same syntax as
                milters (see Section "X -- Mail Filter










SMM:08-142         Sendmail Installation and Operation Guide


                (Milter) Definitions") to specify the remote
                endpoint, e.g.,

                    Ksocket mySocketMap inet:12345@127.0.0.1


                If multiple socket maps define the same
                remote endpoint, they will share a single
                connection to this endpoint.

           Most of these accept as arguments the same
      optional flags and a filename (or a mapname for NIS;
      the filename is the root of the database path, so that
      ".db" or some other extension appropriate for the
      database type will be added to get the actual database
      name).  Known flags are:

      -o        Indicates that this map is optional -- that
                is, if it cannot be opened, no error is
                produced, and sendmail will behave as if the
                map existed but was empty.

      -N, -O    If neither -N or -O are specified, sendmail
                uses an adaptive algorithm to decide whether
                or not to look for null bytes on the end of
                keys.  It starts by trying both; if it finds
                any key with a null byte it never tries
                again without a null byte and vice versa.
                If -N is specified it never tries without a
                null byte and if -O is specified it never
                tries with a null byte.  Setting one of
                these can speed matches but are never
                necessary.  If both -N and -O are specified,
                sendmail will never try any matches at all
                -- that is, everything will appear to fail.

      -ax       Append the string x on successful matches.
                For example, the default host map appends a
                dot on successful matches.

      -Tx       Append the string x on temporary failures.
                For example, x would be appended if a DNS
                lookup returned "server failed" or an NIS
                lookup could not locate a server.  See also
                the -t flag.

      -f        Do not fold upper to lower case before
                looking up the key.

      -m        Match only (without replacing the value).
                If you only care about the existence of a
                key and not the value (as you might when
                searching the NIS map "hosts.byname" for










Sendmail Installation and Operation Guide         SMM:08-143


                example), this flag prevents the map from
                substituting the value.  However, The -a
                argument is still appended on a match, and
                the default is still taken if the match
                fails.

      -kkeycol  The key column name (for NIS+) or number
                (for text lookups).  For LDAP maps this is
                an LDAP filter string in which %s is
                replaced with the literal contents of the
                lookup key and %0 is replaced with the LDAP
                escaped contents of the lookup key according
                to RFC 2254.  If the flag -K is used, then
                %1 through %9 are replaced with the LDAP
                escaped contents of the arguments specified
                in the map lookup.

      -vvalcol  The value column name (for NIS+) or number
                (for text lookups).  For LDAP maps this is
                the name of one or more attributes to be
                returned; multiple attributes can be
                separated by commas.  If not specified, all
                attributes found in the match will be
                returned.  The attributes listed can also
                include a type and one or more objectClass
                values for matching as described in the LDAP
                section.

      -zdelim   The column delimiter (for text lookups).  It
                can be a single character or one of the
                special strings "\n" or "\t" to indicate
                newline or tab respectively.  If omitted
                entirely, the column separator is any
                sequence of white space.  For LDAP and some
                other maps this is the separator character
                to combine multiple values into a single
                return string.  If not set, the LDAP lookup
                will only return the first match found.  For
                DNS maps this is the separator character at
                which the result of a query is cut off if is
                too long.

      -t        Normally, when a map attempts to do a lookup
                and the server fails (e.g., sendmail
                couldn't contact any name server; this is
                not the same as an entry not being found in
                the map), the message being processed is
                queued for future processing.  The -t flag
                turns off this behavior, letting the
                temporary failure (server down) act as
                though it were a permanent failure (entry
                not found).  It is particularly useful for
                DNS lookups, where someone else's










SMM:08-144         Sendmail Installation and Operation Guide


                misconfigured name server can cause problems
                on your machine.  However, care must be
                taken to ensure that you don't bounce mail
                that would be resolved correctly if you
                tried again.  A common strategy is to
                forward such mail to another, possibly
                better connected, mail server.

      -D        Perform no lookup in deferred delivery mode.
                This flag is set by default for the host
                map.

      -Sspacesub
                The character to use to replace space
                characters after a successful map lookup
                (esp. useful for regex and syslog maps).

      -sspacesub
                For the dequote map only, the character to
                use to replace space characters after a
                successful dequote.

      -q        Don't dequote the key before lookup.

      -Llevel   For the syslog map only, it specifies the
                level to use for the syslog call.

      -A        When rebuilding an alias file, the -A flag
                causes duplicate entries in the text version
                to be merged.  For example, two entries:

                    list:    user1, user2
                    list:    user3

                would be treated as though it were the
                single entry

                    list:    user1, user2, user3

                in the presence of the -A flag.

           Some additional flags are available for the host
      and dns maps:

      -d        delay: specify the resolver's retransmission
                time interval (in seconds).

      -r        retry: specify the number of times to
                retransmit a resolver query.

           The dns map has another flag:












Sendmail Installation and Operation Guide         SMM:08-145


      -B        basedomain: specify a domain that is always
                appended to queries.

           Socket maps have an optional flag:

      -d        timeout: specify the timeout (in seconds)
                for communication with the socket map
                server.

           The following additional flags are present in the
      ldap map only:

      -R        Do not auto chase referrals.  sendmail must
                be compiled with -DLDAP_REFERRALS to use
                this flag.

      -n        Retrieve attribute names only.

      -Vsep     Retrieve both attributes name and value(s),
                separated by sep.

      -rderef   Set the alias dereference option to one of
                never, always, search, or find.

      -sscope   Set search scope to one of base, one (one
                level), or sub (subtree).

      -hhost    LDAP server hostname.  Some LDAP libraries
                allow you to specify multiple, space-
                separated hosts for redundancy.  In
                addition, each of the hosts listed can be
                followed by a colon and a port number to
                override the default LDAP port.

      -pport    LDAP service port.

      -H LDAPURI
                Use the specified LDAP URI instead of
                specifying the hostname and port separately
                with the the -h and -p options shown above.
                For example,

                    -h server.example.com -p 389 -b dc=example,dc=com

                is equivalent to

                    -H ldap://server.example.com:389 -b dc=example,dc=com

                If the LDAP library supports it, the LDAP
                URI format however can also request LDAP
                over SSL by using ldaps:// instead of
                ldap://.  For example:











SMM:08-146         Sendmail Installation and Operation Guide


                    O LDAPDefaultSpec=-H ldaps://ldap.example.com -b dc=example,dc=com

                Similarly, if the LDAP library supports it,
                It can also be used to specify a UNIX domain
                socket using ldapi://:

                    O LDAPDefaultSpec=-H ldapi://socketfile -b dc=example,dc=com


      -bbase    LDAP search base.

      -ltimelimit
                Time limit for LDAP queries.

      -Zsizelimit
                Size (number of matches) limit for LDAP or
                DNS queries.

      -ddistinguished_name
                The distinguished name to use to login to
                the LDAP server.

      -Mmethod  The method to authenticate to the LDAP
                server.  Should be one of LDAP_AUTH_NONE,
                LDAP_AUTH_SIMPLE, or LDAP_AUTH_KRBV4.  The
                leading LDAP_AUTH_ can be omitted and the
                value is case-insensitive.

      -Ppasswordfile
                The file containing the secret key for the
                LDAP_AUTH_SIMPLE authentication method or
                the name of the Kerberos ticket file for
                LDAP_AUTH_KRBV4.

      -1        Force LDAP searches to only succeed if a
                single match is found.  If multiple values
                are found, the search is treated as if no
                match was found.

      -wversion Set the LDAP API/protocol version to use.
                The default depends on the LDAP client
                libraries in use.  For example, -w 3 will
                cause sendmail to use LDAPv3 when
                communicating with the LDAP server.

      -K        Treat the LDAP search key as multi-argument
                and replace %1 through %9 in the key with
                the LDAP escaped contents of the lookup
                arguments specified in the map lookup.

           The dbm map appends the strings ".pag" and ".dir"
      to the given filename; the hash and btree maps append
      ".db".  For example, the map specification










Sendmail Installation and Operation Guide         SMM:08-147


          Kuucp dbm -o -N /etc/mail/uucpmap

      specifies an optional map named "uucp" of class "dbm";
      it always has null bytes at the end of every string,
      and the data is located in
      /etc/mail/uucpmap.{dir,pag}.

           The program makemap(8) can be used to build
      database-oriented maps.  It takes at least the
      following flags (for a complete list see its man
      page):

      -f        Do not fold upper to lower case in the map.

      -N        Include null bytes in keys.

      -o        Append to an existing (old) file.

      -r        Allow replacement of existing keys;
                normally, re-inserting an existing key is an
                error.

      -v        Print what is happening.

      The sendmail daemon does not have to be restarted to
      read the new maps as long as you change them in place;
      file locking is used so that the maps won't be read
      while they are being updated.

           New classes can be added in the routine setupmaps
      in file conf.c.

   5.10.  Q -- Queue Group Declaration

           In addition to the option QueueDirectory, queue
      groups can be declared that define a (group of) queue
      directories under a common name.  The syntax is as
      follows:

          Qname {, field=value}+

      where name is the symbolic name of the queue group
      under which it can be referenced in various places and
      the "field=value" pairs define attributes of the queue
      group.  The name must only consist of alphanumeric
      characters.  Fields are:

      Flags     Flags for this queue group.

      Nice      The nice(2) increment for the queue group.
                This value must be greater or equal zero.












SMM:08-148         Sendmail Installation and Operation Guide


      Interval  The time between two queue runs.

      Path      The queue directory of the group (required).

      Runners   The number of parallel runners processing
                the queue.  Note that F=f must be set if
                this value is greater than one.

      Jobs      The maximum number of jobs (messages
                delivered) per queue run.

      recipients
                The maximum number of recipients per
                envelope.  Envelopes with more than this
                number of recipients will be split into
                multiple envelopes in the same queue
                directory.  The default value 0 means no
                limit.

      Only the first character of the field name is checked.

           By default, a queue group named mqueue is defined
      that uses the value of the QueueDirectory option as
      path.  Notice: all paths that are used for queue
      groups must be subdirectories of QueueDirectory.
      Since they can be symbolic links, this isn't a real
      restriction, If QueueDirectory uses a wildcard, then
      the directory one level up is considered the ``base''
      directory which all other queue directories must
      share.  Please make sure that the queue directories do
      not overlap, e.g., do not specify

          O QueueDirectory=/var/spool/mqueue/*
          Qone, P=/var/spool/mqueue/dir1
          Qtwo, P=/var/spool/mqueue/dir2

      because this also includes "dir1" and "dir2" in the
      default queue group.  However,

          O QueueDirectory=/var/spool/mqueue/main*
          Qone, P=/var/spool/mqueue/dir
          Qtwo, P=/var/spool/mqueue/other*

      is a valid queue group specification.

           Options listed in the ``Flags'' field can be used
      to modify the behavior of a queue group.  The ``f''
      flag must be set if multiple queue runners are
      supposed to work on the entries in a queue group.
      Otherwise sendmail will work on the entries strictly
      sequentially.












Sendmail Installation and Operation Guide         SMM:08-149


           The ``Interval'' field sets the time between
      queue runs.  If no queue group specific interval is
      set, then the parameter of the -q option from the
      command line is used.

           To control the overall number of concurrently
      active queue runners the option MaxQueueChildren can
      be set.  This limits the number of processes used for
      running the queues to MaxQueueChildren, though at any
      one time fewer processes may be active as a result of
      queue options, completed queue runs, system load, etc.

           The maximum number of queue runners for an
      individual queue group can be controlled via the
      Runners option.  If set to 0, entries in the queue
      will not be processed, which is useful to
      ``quarantine'' queue files.  The number of runners per
      queue group may also be set with the option
      MaxRunnersPerQueue, which applies to queue groups that
      have no individual limit.  That is, the default value
      for Runners is MaxRunnersPerQueue if set, otherwise 1.

           The field Jobs describes the maximum number of
      jobs (messages delivered) per queue run, which is the
      queue group specific value of MaxQueueRunSize.

           Notice: queue groups should be declared after all
      queue related options have been set because queue
      groups take their defaults from those options.  If an
      option is set after a queue group declaration, the
      values of options in the queue group are set to the
      defaults of sendmail unless explicitly set in the
      declaration.

           Each envelope is assigned to a queue group based
      on the algorithm described in section ``Queue Groups
      and Queue Directories''.

   5.11.  X -- Mail Filter (Milter) Definitions

           The sendmail Mail Filter API (Milter) is designed
      to allow third-party programs access to mail messages
      as they are being processed in order to filter meta-
      information and content.  They are declared in the
      configuration file as:

          Xname {, field=value}*

      where name is the name of the filter (used internally
      only) and the "field=name" pairs define attributes of
      the filter.  Also see the documentation for the
      InputMailFilters option for more information.











SMM:08-150         Sendmail Installation and Operation Guide


           Fields are:

          Socket    The socket specification
          Flags     Special flags for this filter
          Timeouts  Timeouts for this filter

      Only the first character of the field name is checked
      (it's case-sensitive).

           The socket specification is one of the following
      forms:

          S=inet: port @ host


          S=inet6: port @ host


          S=local: path

      The first two describe an IPv4 or IPv6 socket
      listening on a certain port at a given host or IP
      address.  The final form describes a named socket on
      the filesystem at the given path.

           The following flags may be set in the filter
      description.

      R   Reject connection if filter unavailable.

      T   Temporary fail connection if filter unavailable.

           If neither F=R nor F=T is specified, the message
      is passed through sendmail in case of filter errors as
      if the failing filters were not present.

           The timeouts can be set using the four fields
      inside of the T= equate:

      C   Timeout for connecting to a filter.  If set to 0,
          the system's connect() timeout will be used.

      S   Timeout for sending information from the MTA to a
          filter.

      R   Timeout for reading reply from the filter.

      E   Overall timeout between sending end-of-message to
          filter and waiting for the final acknowledgment.

           Note the separator between each timeout field is
      a ';'.  The default values (if not set) are:
      T=C:5m;S:10s;R:10s;E:5m where s is seconds and m is










Sendmail Installation and Operation Guide         SMM:08-151


      minutes.

           Examples:

          Xfilter1, S=local:/var/run/f1.sock, F=R
          Xfilter2, S=inet6:999@localhost, F=T, T=S:1s;R:1s;E:5m
          Xfilter3, S=inet:3333@localhost, T=C:2m


   5.12.  The User Database

           The user database is deprecated in favor of
      ``virtusertable'' and ``genericstable'' as explained
      in the file cf/README.  If you have a version of
      sendmail with the user database package compiled in,
      the handling of sender and recipient addresses is
      modified.

           The location of this database is controlled with
      the UserDatabaseSpec option.

      5.12.1.  Structure of the user database

              The database is a sorted (BTree-based)
         structure.  User records are stored with the key:

             user-name:field-name

         The sorted database format ensures that user
         records are clustered together.  Meta-information
         is always stored with a leading colon.

              Field names define both the syntax and
         semantics of the value.  Defined fields include:

         maildrop  The delivery address for this user.
                   There may be multiple values of this
                   record.  In particular, mailing lists
                   will have one maildrop record for each
                   user on the list.

         mailname  The outgoing mailname for this user.  For
                   each outgoing name, there should be an
                   appropriate maildrop record for that name
                   to allow return mail.  See also
                   :default:mailname.

         mailsender
                   Changes any mail sent to this address to
                   have the indicated envelope sender.  This
                   is intended for mailing lists, and will
                   normally be the name of an appropriate
                   -request address.  It is very similar to










SMM:08-152         Sendmail Installation and Operation Guide


                   the owner-list syntax in the alias file.

         fullname  The full name of the user.

         office-address
                   The office address for this user.

         office-phone
                   The office phone number for this user.

         office-fax
                   The office FAX number for this user.

         home-address
                   The home address for this user.

         home-phone
                   The home phone number for this user.

         home-fax  The home FAX number for this user.

         project   A (short) description of the project this
                   person is affiliated with.  In the
                   University this is often just the name of
                   their graduate advisor.

         plan      A pointer to a file from which plan
                   information can be gathered.

              As of this writing, only a few of these fields
         are actually being used by sendmail: maildrop and
         mailname.  A finger program that uses the other
         fields is planned.

      5.12.2.  User database semantics

              When the rewriting rules submit an address to
         the local mailer, the user name is passed through
         the alias file.  If no alias is found (or if the
         alias points back to the same address), the name
         (with ":maildrop" appended) is then used as a key
         in the user database.  If no match occurs (or if
         the maildrop points at the same address),
         forwarding is tried.

              If the first token of the user name returned
         by ruleset 0 is an "@" sign, the user database
         lookup is skipped.  The intent is that the user
         database will act as a set of defaults for a
         cluster (in our case, the Computer Science
         Division); mail sent to a specific machine should
         ignore these defaults.











Sendmail Installation and Operation Guide         SMM:08-153


              When mail is sent, the name of the sending
         user is looked up in the database.  If that user
         has a "mailname" record, the value of that record
         is used as their outgoing name.  For example, I
         might have a record:

             eric:mailnameEric.Allman@CS.Berkeley.EDU

         This would cause my outgoing mail to be sent as
         Eric.Allman.

              If a "maildrop" is found for the user, but no
         corresponding "mailname" record exists, the record
         ":default:mailname" is consulted.  If present, this
         is the name of a host to override the local host.
         For example, in our case we would set it to
         "CS.Berkeley.EDU".  The effect is that anyone known
         in the database gets their outgoing mail stamped as
         "user@CS.Berkeley.EDU", but people not listed in
         the database use the local hostname.

      5.12.3.  Creating the database[23]

              The user database is built from a text file
         using the makemap utility (in the distribution in
         the makemap subdirectory).  The text file is a
         series of lines corresponding to userdb records;
         each line has a key and a value separated by white
         space.  The key is always in the format described
         above -- for example:

             eric:maildrop

         This file is normally installed in a system
         directory; for example, it might be called
         /etc/mail/userdb.  To make the database version of
         the map, run the program:

             makemap btree /etc/mail/userdb < /etc/mail/userdb

         Then create a config file that uses this.  For
         example, using the V8 M4 configuration, include the
         following line in your .mc file:

             define(`confUSERDB_SPEC', /etc/mail/userdb)

____________________
   [23]These instructions are known to be incomplete.  Other
features  are available which provide similar functionality,
e.g., virtual hosting and mapping  local  addresses  into  a
generic form as explained in cf/README.












SMM:08-154         Sendmail Installation and Operation Guide


6.  OTHER CONFIGURATION

        There are some configuration changes that can be
   made by recompiling sendmail.  This section describes
   what changes can be made and what has to be modified to
   make them.  In most cases this should be unnecessary
   unless you are porting sendmail to a new environment.

   6.1.  Parameters in devtools/OS/$oscf

           These parameters are intended to describe the
      compilation environment, not site policy, and should
      normally be defined in the operating system
      configuration file.  This section needs a complete
      rewrite.

      NDBM      If set, the new version of the DBM library
                that allows multiple databases will be used.
                If neither CDB, NDBM, nor NEWDB are set, a
                much less efficient method of alias lookup
                is used.

      CWDB      If set, use the cdb (tinycdb) package.

      NEWDB     If set, use the new database package from
                Berkeley (from 4.4BSD).  This package is
                substantially faster than DBM or NDBM.  If
                NEWDB and NDBM are both set, sendmail will
                read DBM files, but will create and use
                NEWDB files.

      NIS       Include support for NIS.  If set together
                with both NEWDB and NDBM, sendmail will
                create both DBM and NEWDB files if and only
                if an alias file includes the substring
                "/yp/" in the name.  This is intended for
                compatibility with Sun Microsystems' mkalias
                program used on YP masters.

      NISPLUS   Compile in support for NIS+.

      NETINFO   Compile in support for NetInfo (NeXT
                stations).

      LDAPMAP   Compile in support for LDAP X500 queries.
                Requires libldap and liblber from the Umich
                LDAP 3.2 or 3.3 release or equivalent
                libraries for other LDAP libraries such as
                OpenLDAP.

      HESIOD    Compile in support for Hesiod.












Sendmail Installation and Operation Guide         SMM:08-155


      MAP_NSD   Compile in support for IRIX NSD lookups.

      MAP_REGEX Compile in support for regular expression
                matching.

      DNSMAP    Compile in support for DNS map lookups in
                the sendmail.cf file.

      PH_MAP    Compile in support for ph lookups.

      SASL      Compile in support for SASL, a required
                component for SMTP Authentication support.

      STARTTLS  Compile in support for STARTTLS.

      EGD       Compile in support for the "Entropy
                Gathering Daemon" to provide better random
                data for TLS.

      TCPWRAPPERS
                Compile in support for TCP Wrappers.

      _PATH_SENDMAILCF
                The pathname of the sendmail.cf file.

      _PATH_SENDMAILPID
                The pathname of the sendmail.pid file.

      SM_CONF_SHM
                Compile in support for shared memory, see
                section about "/var/spool/mqueue".

      MILTER    Compile in support for contacting external
                mail filters built with the Milter API.

           There are also several compilation flags to
      indicate the environment such as "_AIX3" and
      "_SCO_unix_".  See the sendmail/README file for the
      latest scoop on these flags.

      6.1.1.  For Future Releases

              sendmail often contains compile time options
         For Future Releases (prefix _FFR_) which might be
         enabled in a subsequent version or might simply be
         removed as they turned out not to be really useful.
         These features are usually not documented but if
         they are, then the required (FFR) compile time
         options are listed here for rulesets and macros,
         and in cf/README for mc/cf options.  FFR compile
         times options must be enabled when the sendmail
         binary is built from source.  Enabled FFRs in a
         binary can be listed with










SMM:08-156         Sendmail Installation and Operation Guide


             sendmail -d0.13 < /dev/null | grep FFR


   6.2.  Parameters in sendmail/conf.h

           Parameters and compilation options are defined in
      conf.h.  Most of these need not normally be tweaked;
      common parameters are all in sendmail.cf.  However,
      the sizes of certain primitive vectors, etc., are
      included in this file.  The numbers following the
      parameters are their default value.

           This document is not the best source of
      information for compilation flags in conf.h -- see
      sendmail/README or sendmail/conf.h itself.

      MAXLINE [2048]
                  The maximum line length of any input line.
                  If message lines exceed this length they
                  will still be processed correctly;
                  however, header lines, configuration file
                  lines, alias lines, etc., must fit within
                  this limit.

      MAXNAME [256]
                  The maximum length of any name, such as a
                  host or a user name.

      MAXPV [256] The maximum number of parameters to any
                  mailer.  This limits the number of
                  recipients that may be passed in one
                  transaction.  It can be set to any
                  arbitrary number above about 10, since
                  sendmail will break up a delivery into
                  smaller batches as needed.  A higher
                  number may reduce load on your system,
                  however.

      MAXQUEUEGROUPS [50]
                  The maximum number of queue groups.

      MAXATOM [1000]
                  The maximum number of atoms (tokens) in a
                  single address.  For example, the address
                  "eric@CS.Berkeley.EDU" is seven atoms.

      MAXMAILERS [25]
                  The maximum number of mailers that may be
                  defined in the configuration file.  This
                  value is defined in
                  include/sendmail/sendmail.h.












Sendmail Installation and Operation Guide         SMM:08-157


      MAXRWSETS [200]
                  The maximum number of rewriting sets that
                  may be defined.  The first half of these
                  are reserved for numeric specification
                  (e.g., ``S92''), while the upper half are
                  reserved for auto-numbering (e.g.,
                  ``Sfoo'').  Thus, with a value of 200 an
                  attempt to use ``S99'' will succeed, but
                  ``S100'' will fail.

      MAXPRIORITIES [25]
                  The maximum number of values for the
                  "Precedence:" field that may be defined
                  (using the P line in sendmail.cf).

      MAXUSERENVIRON [100]
                  The maximum number of items in the user
                  environment that will be passed to
                  subordinate mailers.

      MAXMXHOSTS [100]
                  The maximum number of MX records we will
                  accept for any single host.

      MAXMAPSTACK [12]
                  The maximum number of maps that may be
                  "stacked" in a sequence class map.

      MAXMIMEARGS [20]
                  The maximum number of arguments in a MIME
                  Content-Type: header; additional arguments
                  will be ignored.

      MAXMIMENESTING [20]
                  The maximum depth to which MIME messages
                  may be nested (that is, nested Message or
                  Multipart documents; this does not limit
                  the number of components in a single
                  Multipart document).

      MAXDAEMONS [10]
                  The maximum number of sockets sendmail
                  will open for accepting connections on
                  different ports.

      MAXMACNAMELEN [25]
                  The maximum length of a macro name.

      A number of other compilation options exist.  These
      specify whether or not specific code should be
      compiled in.  Ones marked with * are 0/1 valued.












SMM:08-158         Sendmail Installation and Operation Guide


      NETINET*    If set, support for Internet protocol
                  networking is compiled in.  Previous
                  versions of sendmail referred to this as
                  DAEMON; this old usage is now incorrect.
                  Defaults on; turn it off in the Makefile
                  if your system doesn't support the
                  Internet protocols.

      NETINET6*   If set, support for IPv6 networking is
                  compiled in.  It must be separately
                  enabled by adding DaemonPortOptions
                  settings.

      NETISO*     If set, support for ISO protocol
                  networking is compiled in (it may be
                  appropriate to #define this in the
                  Makefile instead of conf.h).

      NETUNIX*    If set, support for UNIX domain sockets is
                  compiled in.  This is used for control
                  socket support.

      LOG         If set, the syslog routine in use at some
                  sites is used.  This makes an
                  informational log record for each message
                  processed, and makes a higher priority log
                  record for internal system errors.
                  STRONGLY RECOMMENDED -- if you want no
                  logging, turn it off in the configuration
                  file.

      MATCHGECOS* Compile in the code to do ``fuzzy
                  matching'' on the GECOS field in
                  /etc/passwd.  This also requires that the
                  MatchGECOS option be turned on.

      NAMED_BIND* Compile in code to use the Berkeley
                  Internet Name Domain (BIND) server to
                  resolve TCP/IP host names.

      NOTUNIX     If you are using a non-UNIX mail format,
                  you can set this flag to turn off special
                  processing of UNIX-style "From " lines.

      USERDB*     Include the experimental Berkeley user
                  information database package.  This adds a
                  new level of local name expansion between
                  aliasing and forwarding.  It also uses the
                  NEWDB package.  This may change in future
                  releases.

      The following options are normally turned on in per-
      operating-system clauses in conf.h.










Sendmail Installation and Operation Guide         SMM:08-159


      IDENTPROTO* Compile in the IDENT protocol as defined
                  in RFC 1413.  This defaults on for all
                  systems except Ultrix, which apparently
                  has the interesting "feature" that when it
                  receives a "host unreachable" message it
                  closes all open connections to that host.
                  Since some firewall gateways send this
                  error code when you access an unauthorized
                  port (such as 113, used by IDENT), Ultrix
                  cannot receive email from such hosts.

      SYSTEM5     Set all of the compilation parameters
                  appropriate for System V.

      HASFLOCK*   Use Berkeley-style flock instead of System
                  V lockf to do file locking.  Due to the
                  highly unusual semantics of locks across
                  forks in lockf, this should always be used
                  if at all possible.

      HASINITGROUPS
                  Set this if your system has the
                  initgroups() call (if you have multiple
                  group support).  This is the default if
                  SYSTEM5 is not defined or if you are on
                  HPUX.

      HASUNAME    Set this if you have the uname(2) system
                  call (or corresponding library routine).
                  Set by default if SYSTEM5 is set.

      HASGETDTABLESIZE
                  Set this if you have the getdtablesize(2)
                  system call.

      HASWAITPID  Set this if you have the haswaitpid(2)
                  system call.

      FAST_PID_RECYCLE
                  Set this if your system can possibly reuse
                  the same pid in the same second of time.

      SFS_TYPE    The mechanism that can be used to get file
                  system capacity information.  The values
                  can be one of SFS_USTAT (use the ustat(2)
                  syscall), SFS_4ARGS (use the four argument
                  statfs(2) syscall), SFS_VFS (use the two
                  argument statfs(2) syscall including
                  <sys/vfs.h>), SFS_MOUNT (use the two
                  argument statfs(2) syscall including
                  <sys/mount.h>), SFS_STATFS (use the two
                  argument statfs(2) syscall including
                  <sys/statfs.h>), SFS_STATVFS (use the two










SMM:08-160         Sendmail Installation and Operation Guide


                  argument statfs(2) syscall including
                  <sys/statvfs.h>), or SFS_NONE (no way to
                  get this information).

      LA_TYPE     The load average type.  Details are
                  described below.

      The are several built-in ways of computing the load
      average.  Sendmail tries to auto-configure them based
      on imperfect guesses; you can select one using the cc
      option -DLA_TYPE=type, where type is:

      LA_INT      The kernel stores the load average in the
                  kernel as an array of long integers.  The
                  actual values are scaled by a factor
                  FSCALE (default 256).

      LA_SHORT    The kernel stores the load average in the
                  kernel as an array of short integers.  The
                  actual values are scaled by a factor
                  FSCALE (default 256).

      LA_FLOAT    The kernel stores the load average in the
                  kernel as an array of double precision
                  floats.

      LA_MACH     Use MACH-style load averages.

      LA_SUBR     Call the getloadavg routine to get the
                  load average as an array of doubles.

      LA_ZERO     Always return zero as the load average.
                  This is the fallback case.

      If type LA_INT, LA_SHORT, or LA_FLOAT is specified,
      you may also need to specify _PATH_UNIX (the path to
      your system binary) and LA_AVENRUN (the name of the
      variable containing the load average in the kernel;
      usually "_avenrun" or "avenrun").

   6.3.  Configuration in sendmail/conf.c

           The following changes can be made in conf.c.

      6.3.1.  Built-in Header Semantics

              Not all header semantics are defined in the
         configuration file.  Header lines that should only
         be included by certain mailers (as well as other
         more obscure semantics) must be specified in the
         HdrInfo table in conf.c.  This table contains the
         header name (which should be in all lower case) and
         a set of header control flags (described below),










Sendmail Installation and Operation Guide         SMM:08-161


         The flags are:

         H_ACHECK    Normally when the check is made to see
                     if a header line is compatible with a
                     mailer, sendmail will not delete an
                     existing line.  If this flag is set,
                     sendmail will delete even existing
                     header lines.  That is, if this bit is
                     set and the mailer does not have flag
                     bits set that intersect with the
                     required mailer flags in the header
                     definition in sendmail.cf, the header
                     line is always deleted.

         H_EOH       If this header field is set, treat it
                     like a blank line, i.e., it will signal
                     the end of the header and the beginning
                     of the message text.

         H_FORCE     Add this header entry even if one
                     existed in the message before.  If a
                     header entry does not have this bit
                     set, sendmail will not add another
                     header line if a header line of this
                     name already existed.  This would
                     normally be used to stamp the message
                     by everyone who handled it.

         H_TRACE     If set, this is a timestamp (trace)
                     field.  If the number of trace fields
                     in a message exceeds a preset amount
                     the message is returned on the
                     assumption that it has an aliasing
                     loop.

         H_RCPT      If set, this field contains recipient
                     addresses.  This is used by the -t flag
                     to determine who to send to when it is
                     collecting recipients from the message.

         H_FROM      This flag indicates that this field
                     specifies a sender.  The order of these
                     fields in the HdrInfo table specifies
                     sendmail's preference for which field
                     to return error messages to.

         H_ERRORSTO  Addresses in this header should receive
                     error messages.

         H_CTE       This header is a Content-Transfer-
                     Encoding header.












SMM:08-162         Sendmail Installation and Operation Guide


         H_CTYPE     This header is a Content-Type header.

         H_BCC       Strip the value from the header (for
                     Bcc:).

         Let's look at a sample HdrInfo specification:

             struct hdrinfo                    HdrInfo[] =
             {
                      /* originator fields, most to least significant  */
                 "resent-sender",              H_FROM,
                 "resent-from",                H_FROM,
                 "sender",                     H_FROM,
                 "from",                       H_FROM,
                 "full-name",                  H_ACHECK,
                 "errors-to",                  H_FROM|H_ERRORSTO,
                      /* destination fields */
                 "to",                         H_RCPT,
                 "resent-to",                  H_RCPT,
                 "cc",                         H_RCPT,
                 "bcc",                        H_RCPT|H_BCC,
                      /* message identification and control */
                 "message",                    H_EOH,
                 "text",                       H_EOH,
                      /* trace fields */
                 "received",                   H_TRACE|H_FORCE,
                      /* miscellaneous fields */
                 "content-transfer-encoding",  H_CTE,
                 "content-type",               H_CTYPE,

                 NULL,                         0,
             };

         This structure indicates that the "To:", "Resent-
         To:", and "Cc:" fields all specify recipient
         addresses.  Any "Full-Name:" field will be deleted
         unless the required mailer flag (indicated in the
         configuration file) is specified.  The "Message:"
         and "Text:" fields will terminate the header; these
         are used by random dissenters around the network
         world.  The "Received:" field will always be added,
         and can be used to trace messages.

              There are a number of important points here.
         First, header fields are not added automatically
         just because they are in the HdrInfo structure;
         they must be specified in the configuration file in
         order to be added to the message.  Any header
         fields mentioned in the configuration file but not
         mentioned in the HdrInfo structure have default
         processing performed; that is, they are added
         unless they were in the message already.  Second,
         the HdrInfo structure only specifies cliched










Sendmail Installation and Operation Guide         SMM:08-163


         processing; certain headers are processed specially
         by ad hoc code regardless of the status specified
         in HdrInfo.  For example, the "Sender:" and "From:"
         fields are always scanned on ARPANET mail to
         determine the sender[24]; this is used to perform
         the "return to sender" function.  The "From:" and
         "Full-Name:" fields are used to determine the full
         name of the sender if possible; this is stored in
         the macro $x and used in a number of ways.

      6.3.2.  Restricting Use of Email

              If it is necessary to restrict mail through a
         relay, the checkcompat routine can be modified.
         This routine is called for every recipient address.
         It returns an exit status indicating the status of
         the message.  The status EX_OK accepts the address,
         EX_TEMPFAIL queues the message for a later try, and
         other values (commonly EX_UNAVAILABLE) reject the
         message.  It is up to checkcompat to print an error
         message (using usrerr) if the message is rejected.
         For example, checkcompat could read:

             int
             checkcompat(to, e)
                 register ADDRESS *to;
                 register ENVELOPE *e;
             {
                 register STAB *s;

                 s = stab("private", ST_MAILER, ST_FIND);
                 if (s != NULL && e->e_from.q_mailer != LocalMailer &&
                     to->q_mailer == s->s_mailer)
                 {
                     usrerr("No private net mail allowed through this machine");
                     return (EX_UNAVAILABLE);
                 }
                 if (MsgSize > 50000 && bitnset(M_LOCALMAILER, to->q_mailer))
                 {
                     usrerr("Message too large for non-local delivery");
                     e->e_flags |= EF_NORETURN;
                     return (EX_UNAVAILABLE);
                 }
                 return (EX_OK);
             }

____________________
   [24]Actually,  this  is  no  longer  true  in  SMTP; this
information is contained in the envelope.  The older ARPANET
protocols  did  not  completely  distinguish  envelope  from
header.












SMM:08-164         Sendmail Installation and Operation Guide


         This would reject messages greater than 50000 bytes
         unless they were local.  The EF_NORETURN flag can
         be set in e->e_flags to suppress the return of the
         actual body of the message in the error return.
         The actual use of this routine is highly dependent
         on the implementation, and use should be limited.

      6.3.3.  New Database Map Classes

              New key maps can be added by creating a class
         initialization function and a lookup function.
         These are then added to the routine setupmaps.

              The initialization function is called as

             xxx_map_init(MAP *map, char *args)

         The map is an internal data structure.  The args is
         a pointer to the portion of the configuration file
         line following the map class name; flags and
         filenames can be extracted from this line.  The
         initialization function must return true if it
         successfully opened the map, false otherwise.

              The lookup function is called as

             xxx_map_lookup(MAP *map, char buf[], char **av, int *statp)

         The map defines the map internally.  The buf has
         the input key.  This may be (and often is) used
         destructively.  The av is a list of arguments
         passed in from the rewrite line.  The lookup
         function should return a pointer to the new value.
         If the map lookup fails, *statp should be set to an
         exit status code; in particular, it should be set
         to EX_TEMPFAIL if recovery is to be attempted by
         the higher level code.

      6.3.4.  Queueing Function

              The routine shouldqueue is called to decide if
         a message should be queued or processed
         immediately.  Typically this compares the message
         priority to the current load average.  The default
         definition is:


















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             bool
             shouldqueue(pri, ctime)
                 long pri;
                 time_t ctime;
             {
                 if (CurrentLA < QueueLA)
                     return false;
                 return (pri > (QueueFactor / (CurrentLA - QueueLA + 1)));
             }

         If the current load average (global variable
         CurrentLA, which is set before this function is
         called) is less than the low threshold load average
         (option x, variable QueueLA), shouldqueue returns
         false immediately (that is, it should not queue).
         If the current load average exceeds the high
         threshold load average (option X, variable
         RefuseLA), shouldqueue returns true immediately.
         Otherwise, it computes the function based on the
         message priority, the queue factor (option q,
         global variable QueueFactor), and the current and
         threshold load averages.

              An implementation wishing to take the actual
         age of the message into account can also use the
         ctime parameter, which is the time that the message
         was first submitted to sendmail.  Note that the pri
         parameter is already weighted by the number of
         times the message has been tried (although this
         tends to lower the priority of the message with
         time); the expectation is that the ctime would be
         used as an "escape clause" to ensure that messages
         are eventually processed.

      6.3.5.  Refusing Incoming SMTP Connections

              The function refuseconnections returns true if
         incoming SMTP connections should be refused.  The
         current implementation is based exclusively on the
         current load average and the refuse load average
         option (option X, global variable RefuseLA):

             bool
             refuseconnections()
             {
                 return (RefuseLA > 0 && CurrentLA >= RefuseLA);
             }

         A more clever implementation could look at more
         system resources.













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      6.3.6.  Load Average Computation

              The routine getla returns the current load
         average (as a rounded integer).  The distribution
         includes several possible implementations.  If you
         are porting to a new environment you may need to
         add some new tweaks.[25]

   6.4.  Configuration in sendmail/daemon.c

           The file sendmail/daemon.c contains a number of
      routines that are dependent on the local networking
      environment.  The version supplied assumes you have
      BSD style sockets.

           In previous releases, we recommended that you
      modify the routine maphostname if you wanted to
      generalize $[ ... $] lookups.  We now recommend that
      you create a new keyed map instead.

   6.5.  LDAP

           In this section we assume that sendmail has been
      compiled with support for LDAP.

      6.5.1.  LDAP Recursion

              LDAP Recursion allows you to add types to the
         search attributes on an LDAP map specification.
         The syntax is:

         -v ATTRIBUTE[:TYPE[:OBJECTCLASS[|OBJECTCLASS|...]]]


              The new TYPEs are:

         NORMAL    This attribute type specifies the
                   attribute to add to the results string.
                   This is the default.

         DN        Any matches for this attribute are
                   expected to have a value of a fully
                   qualified distinguished name.  sendmail
                   will lookup that DN and apply the
                   attributes requested to the returned DN
                   record.


____________________
   [25]If    you    do,    please    send     updates     to
sendmail@Sendmail.ORG.












Sendmail Installation and Operation Guide         SMM:08-167


         FILTER    Any matches for this attribute are
                   expected to have a value of an LDAP
                   search filter.  sendmail will perform a
                   lookup with the same parameters as the
                   original search but replaces the search
                   filter with the one specified here.

         URL       Any matches for this attribute are
                   expected to have a value of an LDAP URL.
                   sendmail will perform a lookup of that
                   URL and use the results from the
                   attributes named in that URL.  Note
                   however that the search is done using the
                   current LDAP connection, regardless of
                   what is specified as the scheme, LDAP
                   host, and LDAP port in the LDAP URL.

         Any untyped attributes are considered NORMAL
         attributes as described above.

              The optional OBJECTCLASS (| separated) list
         contains the objectClass values for which that
         attribute applies.  If the list is given, the
         attribute named will only be used if the LDAP
         record being returned is a member of that object
         class.  Note that if these new value attribute
         TYPEs are used in an AliasFile option setting, it
         will need to be double quoted to prevent sendmail
         from misparsing the colons.

              Note that LDAP recursion attributes which do
         not ultimately point to an LDAP record are not
         considered an error.

         6.5.1.1.  Example

                 Since examples usually help clarify, here
            is an example which uses all four of the new
            types:

                O LDAPDefaultSpec=-h ldap.example.com -b dc=example,dc=com

                Kexample ldap
                         -z,
                         -k (&(objectClass=sendmailMTAAliasObject)(sendmailMTAKey=%0))
                         -v sendmailMTAAliasValue,mail:NORMAL:inetOrgPerson,
                            uniqueMember:DN:groupOfUniqueNames,
                            sendmailMTAAliasSearch:FILTER:sendmailMTAAliasObject,
                            sendmailMTAAliasURL:URL:sendmailMTAAliasObject


                 That definition specifies that:











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             + Any value in a sendmailMTAAliasValue
               attribute will be added to the result string
               regardless of object class.
             + The mail attribute will be added to the
               result string if the LDAP record is a member
               of the inetOrgPerson object class.
             + The uniqueMember attribute is a recursive
               attribute, used only in groupOfUniqueNames
               records, and should contain an LDAP DN
               pointing to another LDAP record.  The desire
               here is to return the mail attribute from
               those DNs.
             + The sendmailMTAAliasSearch attribute and
               sendmailMTAAliasURL are both used only if
               referenced in a sendmailMTAAliasObject.  They
               are both recursive, the first for a new LDAP
               search string and the latter for an LDAP URL.

   6.6.  STARTTLS

           In this section we assume that sendmail has been
      compiled with support for STARTTLS.  To properly
      understand the use of STARTTLS in sendmail, it is
      necessary to understand at least some basics about
      X.509 certificates and public key cryptography.  This
      information can be found in books about SSL/TLS or on
      WWW sites, e.g., "https://www.OpenSSL.org/".

      6.6.1.  Certificates for STARTTLS

              When acting as a server, sendmail requires
         X.509 certificates to support STARTTLS: one as
         certificate for the server (ServerCertFile and
         corresponding private ServerKeyFile) at least one
         root CA (CACertFile), i.e., a certificate that is
         used to sign other certificates, and a path to a
         directory which contains (zero or more) other CAs
         (CACertPath).  The file specified via CACertFile
         can contain several certificates of CAs.  The DNs
         of these certificates are sent to the client during
         the TLS handshake (as part of the
         CertificateRequest) as the list of acceptable CAs.
         However, do not list too many root CAs in that
         file, otherwise the TLS handshake may fail; e.g.,

             error:14094417:SSL routines:SSL3_READ_BYTES:
             sslv3 alert illegal parameter:s3_pkt.c:964:SSL alert number 47

         You should probably put only the CA cert into that
         file that signed your own cert(s), or at least only
         those you trust.  The CACertPath directory must
         contain the hashes of each CA certificate as
         filenames (or as links to them).  Symbolic links










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         can be generated with the following two (Bourne)
         shell commands:

             C=FileName_of_CA_Certificate
             ln -s $C `openssl x509 -noout -hash < $C`.0

         A better way to do this is to use the c_rehash
         command that is part of the OpenSSL distribution
         because it handles subject hash collisions by
         incrementing the number in the suffix of the
         filename of the symbolic link, e.g., .0 to .1, and
         so on.  An X.509 certificate is also required for
         authentication in client mode (ClientCertFile and
         corresponding private ClientKeyFile), however,
         sendmail will always use STARTTLS when offered by a
         server.  The client and server certificates can be
         identical.  Certificates can be obtained from a
         certificate authority or created with the help of
         OpenSSL.  The required format for certificates and
         private keys is PEM.  To allow for automatic
         startup of sendmail, private keys (ServerKeyFile,
         ClientKeyFile) must be stored unencrypted.  The
         keys are only protected by the permissions of the
         file system.  Never make a private key available to
         a third party.

              The options ClientCertFile, ClientKeyFile,
         ServerCertFile, and ServerKeyFile can take a second
         file name, which must be separated from the first
         with a comma (note: do not use any spaces) to set
         up a second cert/key pair.  This can be used to
         have certs of different types, e.g., RSA and DSA.

      6.6.2.  PRNG for STARTTLS

              STARTTLS requires a strong pseudo random
         number generator (PRNG) to operate properly.
         Depending on the TLS library you use, it may be
         required to explicitly initialize the PRNG with
         random data.  OpenSSL makes use of /dev/urandom(4)
         if available (this corresponds to the compile flag
         HASURANDOMDEV).  On systems which lack this
         support, a random file must be specified in the
         sendmail.cf file using the option RandFile.  It is
         strongly advised to use the "Entropy Gathering
         Daemon" EGD from Brian Warner on those systems to
         provide useful random data.  In this case, sendmail
         must be compiled with the flag EGD, and the
         RandFile option must point to the EGD socket.  If
         neither /dev/urandom(4) nor EGD are available, you
         have to make sure that useful random data is
         available all the time in RandFile.  If the file
         hasn't been modified in the last 10 minutes before










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         it is supposed to be used by sendmail the content
         is considered obsolete.  One method for generating
         this file is:

             openssl rand -out /etc/mail/randfile -rand /path/to/file:...256

         See the OpenSSL documentation for more information.
         In this case, the PRNG for TLS is only seeded with
         other random data if the DontBlameSendmail option
         InsufficientEntropy is set.  This is most likely
         not sufficient for certain actions, e.g.,
         generation of (temporary) keys.

              Please see the OpenSSL documentation or other
         sources for further information about certificates,
         their creation and their usage, the importance of a
         good PRNG, and other aspects of TLS.

   6.7.  Encoding of STARTTLS and AUTH related Macros

           Macros that contain STARTTLS and AUTH related
      data which comes from outside sources, e.g., all
      macros containing information from certificates, are
      encoded to avoid problems with non-printable or
      special characters.  The latter are '\', '<', '>',
      '(', ')', '"', '+', and ' '.  All of these characters
      are replaced by their value in hexadecimal with a
      leading '+'.  For example:

          /C=US/ST=California/O=endmail.org/OU=private/CN=Darth Mail (Cert)/
          Email=darth+cert@endmail.org

      is encoded as:

          /C=US/ST=California/O=endmail.org/OU=private/
          CN=Darth+20Mail+20+28Cert+29/Email=darth+2Bcert@endmail.org

      (line breaks have been inserted for readability).  The
      macros which are subject to this encoding are
      {cert_subject}, {cert_issuer}, {cn_subject},
      {cn_issuer}, as well as {auth_authen} and
      {auth_author}.

   6.8.  DANE

           Experimental, partial support for DANE (see RFC
      7672 et.al.)  is available if sendmail is compiled
      with the option _FFR_TLSA_DANE.  Only TLSA RR 3-1-1
      (DANE-EE) is currently implemented and the port is
      hardcoded to 25.  The option

          O DANE=true











Sendmail Installation and Operation Guide         SMM:08-171


      enables this feature at run time and it automatically
      adds use_dnssec and use_edns0 to

          O ResolverOptions

      If the client finds a usable TLSA RR and the check
      succeeds the macro ${verify} is set to TRUSTED.  All
      non-DNS maps are considered secure just like DNS
      lookups with DNSSEC.

7.  ACKNOWLEDGEMENTS

        I've worked on sendmail for many years, and many
   employers have been remarkably patient about letting me
   work on a large project that was not part of my official
   job.  This includes time on the INGRES Project at the
   University of California at Berkeley, at Britton Lee, and
   again on the Mammoth and Titan Projects at Berkeley.

        Much of the second wave of improvements resulting in
   version 8.1 should be credited to Bryan Costales of the
   International Computer Science Institute.  As he passed
   me drafts of his book on sendmail I was inspired to start
   working on things again.  Bryan was also available to
   bounce ideas off of.

        Gregory Neil Shapiro of Worcester Polytechnic
   Institute has become instrumental in all phases of
   sendmail support and development, and was largely
   responsible for getting versions 8.8 and 8.9 out the
   door.

        Many, many people contributed chunks of code and
   ideas to sendmail.  It has proven to be a group network
   effort.  Version 8 in particular was a group project.
   The following people and organizations made notable
   contributions:

       Claus Assmann
       John Beck, Hewlett-Packard & Sun Microsystems
       Keith Bostic, CSRG, University of California, Berkeley
       Andrew Cheng, Sun Microsystems
       Michael J. Corrigan, University of California, San Diego
       Bryan Costales, International Computer Science Institute & InfoBeat
       Par (Pell) Emanuelsson
       Craig Everhart, Transarc Corporation
       Per Hedeland, Ericsson
       Tom Ivar Helbekkmo, Norwegian School of Economics
       Kari Hurtta, Finnish Meteorological Institute
       Allan E. Johannesen, WPI
       Jonathan Kamens, OpenVision Technologies, Inc.
       Takahiro Kanbe, Fuji Xerox Information Systems Co., Ltd.
       Brian Kantor, University of California, San Diego










SMM:08-172         Sendmail Installation and Operation Guide


       John Kennedy, Cal State University, Chico
       Murray S. Kucherawy, HookUp Communication Corp.
       Bruce Lilly, Sony U.S.
       Karl London
       Motonori Nakamura, Ritsumeikan University & Kyoto University
       John Gardiner Myers, Carnegie Mellon University
       Neil Rickert, Northern Illinois University
       Gregory Neil Shapiro, WPI
       Eric Schnoebelen, Convex Computer Corp.
       Eric Wassenaar, National Institute for Nuclear and High Energy Physics, Amsterdam
       Randall Winchester, University of Maryland
       Christophe Wolfhugel, Pasteur Institute & Herve Schauer Consultants (Paris)
       Exactis.com, Inc.

   I apologize for anyone I have omitted, misspelled,
   misattributed, or otherwise missed.  At this point, I
   suspect that at least a hundred people have contributed
   code, and many more have contributed ideas, comments, and
   encouragement.  I've tried to list them in the
   RELEASE_NOTES in the distribution directory.  I
   appreciate their contribution as well.

        Special thanks are reserved for Michael Corrigan and
   Christophe Wolfhugel, who besides being wonderful guinea
   pigs and contributors have also consented to be added to
   the ``sendmail@Sendmail.ORG'' list and, by answering the
   bulk of the questions sent to that list, have freed me up
   to do other work.






































                          APPENDIX  A


                      COMMAND LINE FLAGS




     Arguments must be presented with flags before
addresses.  The flags are:

-Ax       Select an alternative .cf file which is either
          sendmail.cf for -Am or submit.cf for -Ac.  By
          default the .cf file is chosen based on the
          operation mode.  For -bm (default), -bs, and -t it
          is submit.cf if it exists, for all others it is
          sendmail.cf.

-bx       Set operation mode to x.  Operation modes are:

              m   Deliver mail (default)
              s   Speak SMTP on input side
              a*  ``Arpanet'' mode (get envelope sender information from header)
              C   Check the configuration file
              d   Run as a daemon in background
              D   Run as a daemon in foreground
              t   Run in test mode
              v   Just verify addresses, don't collect or deliver
              i   Initialize the alias database
              p   Print the mail queue
              P   Print overview over the mail queue (requires shared memory)
              h   Print the persistent host status database
              H   Purge expired entries from the persistent host status database


-Btype    Indicate body type.

-Cfile    Use a different configuration file.  Sendmail runs
          as the invoking user (rather than root) when this
          flag is specified.

-D logfile
          Send debugging output to the indicated logfile
          instead of stdout.

-dlevel   Set debugging level.

-f addr   The envelope sender address is set to addr.  This
          address may also be used in the From: header if
____________________
   *Deprecated.




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          that header is missing during initial submission.
          The envelope sender address is used as the
          recipient for delivery status notifications and
          may also appear in a Return-Path: header.

-F name   Sets the full name of this user to name.

-G        When accepting messages via the command line,
          indicate that they are for relay (gateway)
          submission.  sendmail may complain about
          syntactically invalid messages, e.g., unqualified
          host names, rather than fixing them when this flag
          is set.  sendmail will not do any canonicalization
          in this mode.

-h cnt    Sets the "hop count" to cnt.  This represents the
          number of times this message has been processed by
          sendmail (to the extent that it is supported by
          the underlying networks).  Cnt is incremented
          during processing, and if it reaches MAXHOP
          (currently 25) sendmail throws away the message
          with an error.

-L tag    Sets the identifier used for syslog.  Note that
          this identifier is set as early as possible.
          However, sendmail may be used if problems arise
          before the command line arguments are processed.

-n        Don't do aliasing or forwarding.

-N notifications
          Tag all addresses being sent as wanting the
          indicated notifications, which consists of the
          word "NEVER" or a comma-separated list of
          "SUCCESS", "FAILURE", and "DELAY" for successful
          delivery, failure, and a message that is stuck in
          a queue somewhere.  The default is
          "FAILURE,DELAY".

-r addr   An obsolete form of -f.

-oxvalue  Set option x to the specified value.  These
          options are described in Section 5.6.

-Ooption=value
          Set option to the specified value (for long form
          option names).  These options are described in
          Section 5.6.

-Mxvalue  Set macro x to the specified value.

-pprotocol
          Set the sending protocol.  Programs are encouraged










Sendmail Installation and Operation Guide         SMM:08-175


          to set this.  The protocol field can be in the
          form protocol:host to set both the sending
          protocol and sending host.  For example,
          "-pUUCP:uunet" sets the sending protocol to UUCP
          and the sending host to uunet.  (Some existing
          programs use -oM to set the r and s macros; this
          is equivalent to using -p.)

-qtime    Try to process the queued up mail.  If the time is
          given, sendmail will start one or more processes
          to run through the queue(s) at the specified time
          interval to deliver queued mail; otherwise, it
          only runs once.  Each of these processes acts on a
          workgroup.  These processes are also known as
          workgroup processes or WGP's for short.  Each
          workgroup is responsible for controlling the
          processing of one or more queues; workgroups help
          manage the use of system resources by sendmail.
          Each workgroup may have one or more children
          concurrently processing queues depending on the
          setting of MaxQueueChildren.

-qptime   Similar to -q with a time argument, except that
          instead of periodically starting WGP's sendmail
          starts persistent WGP's that alternate between
          processing queues and sleeping.  The sleep time is
          specified by the time argument; it defaults to 1
          second, except that a WGP always sleeps at least 5
          seconds if their queues were empty in the previous
          run.  Persistent processes are managed by a queue
          control process (QCP).  The QCP is the parent
          process of the WGP's.  Typically the QCP will be
          the sendmail daemon (when started with -bd or -bD)
          or a special process (named Queue control) (when
          started without -bd or -bD).  If a persistent WGP
          ceases to be active for some reason another WGP
          will be started by the QCP for the same workgroup
          in most cases. When a persistent WGP has core
          dumped, the debug flag no_persistent_restart is
          set or the specific persistent WGP has been
          restarted too many times already then the WGP will
          not be started again and a message will be logged
          to this effect.  To stop (SIGTERM) or restart
          (SIGHUP) persistent WGP's the appropriate signal
          should be sent to the QCP. The QCP will propagate
          the signal to all of the WGP's and if appropriate
          restart the persistent WGP's.

-qGname   Run the jobs in the queue group name once.

-q[!]Xstring
          Run the queue once, limiting the jobs to those
          matching Xstring.  The key letter X can be I to










SMM:08-176         Sendmail Installation and Operation Guide


          limit based on queue identifier, R to limit based
          on recipient, S to limit based on sender, or Q to
          limit based on quarantine reason for quarantined
          jobs.  A particular queued job is accepted if one
          of the corresponding attributes contains the
          indicated string.  The optional ! character
          negates the condition tested.  Multiple -qX flags
          are permitted, with items with the same key letter
          "or'ed" together, and items with different key
          letters "and'ed" together.

-Q[reason]
          Quarantine normal queue items with the given
          reason or unquarantine quarantined queue items if
          no reason is given.  This should only be used with
          some sort of item matching using -q[!]Xstring as
          described above.

-R ret    What information you want returned if the message
          bounces; ret can be "HDRS" for headers only or
          "FULL" for headers plus body.  This is a request
          only; the other end is not required to honor the
          parameter.  If "HDRS" is specified local bounces
          also return only the headers.

-t        Read the header for "To:", "Cc:", and "Bcc:"
          lines, and send to everyone listed in those lists.
          The "Bcc:" line will be deleted before sending.
          Any addresses in the argument vector will be
          deleted from the send list.

-V envid  The indicated envid is passed with the envelope of
          the message and returned if the message bounces.

-X logfile
          Log all traffic in and out of sendmail in the
          indicated logfile for debugging mailer problems.
          This produces a lot of data very quickly and
          should be used sparingly.

     There are a number of options that may be specified as
primitive flags.  These are the e, i, m, and v options.
Also, the f option may be specified as the -s flag.  The DSN
related options "-N", "-R", and "-V" have no effects on
sendmail running as daemon.





















                        APPENDIX  B


                     QUEUE FILE FORMATS




     This appendix describes the format of the queue files.
These files live in a queue directory.  The individual qf,
hf, Qf, df, and xf files may be stored in separate qf/, df/,
and xf/ subdirectories if they are present in the queue
directory.

     All queue files have the name ttYMDhmsNNppppp where
YMDhmsNNppppp is the id for this message and the tt is a
type.  The individual letters in the id are:

Y    Encoded year

M    Encoded month

D    Encoded day

h    Encoded hour

m    Encoded minute

s    Encoded second

NN   Encoded envelope number

ppppp
     At least five decimal digits of the process ID

     All files with the same id collectively define one
message.  Due to the use of memory-buffered files, some of
these files may never appear on disk.

     The types are:

qf   The queue control file.  This file contains the
     information necessary to process the job.

hf   The same as a queue control file, but for a quarantined
     queue job.

df   The data file.  The message body (excluding the header)
     is kept in this file.  Sometimes the df file is not
     stored in the same directory as the qf file; in this
     case, the qf file contains a `d' record which names the
     queue directory that contains the df file.



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SMM:08-178         Sendmail Installation and Operation Guide


tf   A temporary file.  This is an image of the qf file when
     it is being rebuilt.  It should be renamed to a qf file
     very quickly.

xf   A transcript file, existing during the life of a
     session showing everything that happens during that
     session.  Sometimes the xf file must be generated
     before a queue group has been selected; in this case,
     the xf file will be stored in a directory of the
     default queue group.

Qf   A ``lost'' queue control file.  sendmail renames a qf
     file to Qf if there is a severe (configuration) problem
     that cannot be solved without human intervention.
     Search the logfile for the queue file id to figure out
     what happened.  After you resolved the problem, you can
     rename the Qf file to qf and send it again.

     The queue control file is structured as a series of
lines each beginning with a code letter.  The lines are as
follows:

V    The version number of the queue file format, used to
     allow new sendmail binaries to read queue files created
     by older versions.  Defaults to version zero.  Must be
     the first line of the file if present.  For 8.12 the
     version number is 6.

A    The information given by the AUTH= parameter of the
     "MAIL FROM:" command or $f@$j if sendmail has been
     called directly.

H    A header definition.  There may be any number of these
     lines.  The order is important: they represent the
     order in the final message.  These use the same syntax
     as header definitions in the configuration file.

C    The controlling address.  The syntax is
     "localuser:aliasname".  Recipient addresses following
     this line will be flagged so that deliveries will be
     run as the localuser (a user name from the /etc/passwd
     file); aliasname is the name of the alias that expanded
     to this address (used for printing messages).

q    The quarantine reason for quarantined queue items.

Q    The ``original recipient'', specified by the ORCPT=
     field in an ESMTP transaction.  Used exclusively for
     Delivery Status Notifications.  It applies only to the
     following `R' line.

r    The ``final recipient'' used for Delivery Status
     Notifications.  It applies only to the following `R'










Sendmail Installation and Operation Guide         SMM:08-179


     line.

R    A recipient address.  This will normally be completely
     aliased, but is actually realiased when the job is
     processed.  There will be one line for each recipient.
     Version 1 qf files also include a leading colon-
     terminated list of flags, which can be `S' to return a
     message on successful final delivery, `F' to return a
     message on failure, `D' to return a message if the
     message is delayed, `B' to indicate that the body
     should be returned, `N' to suppress returning the body,
     and `P' to declare this as a ``primary'' (command line
     or SMTP-session) address.

S    The sender address.  There may only be one of these
     lines.

T    The job creation time.  This is used to compute when to
     time out the job.

P    The current message priority.  This is used to order
     the queue.  Higher numbers mean lower priorities.  The
     priority changes as the message sits in the queue.  The
     initial priority depends on the message class and the
     size of the message.

M    A message.  This line is printed by the mailq command,
     and is generally used to store status information.  It
     can contain any text.

F    Flag bits, represented as one letter per flag.  Defined
     flag bits are r indicating that this is a response
     message and w indicating that a warning message has
     been sent announcing that the mail has been delayed.
     Other flag bits are: 8: the body contains 8bit data, b:
     a Bcc: header should be removed, d: the mail has RET
     parameters (see RFC 1894), n: the body of the message
     should not be returned in case of an error, s: the
     envelope has been split.

N    The total number of delivery attempts.

K    The time (as seconds since January 1, 1970) of the last
     delivery attempt.

d    If the df file is in a different directory than the qf
     file, then a `d' record is present, specifying the
     directory in which the df file resides.

I    The i-number of the data file; this can be used to
     recover your mail queue after a disastrous disk crash.












SMM:08-180         Sendmail Installation and Operation Guide


$    A macro definition.  The values of certain macros are
     passed through to the queue run phase.

B    The body type.  The remainder of the line is a text
     string defining the body type.  If this field is
     missing, the body type is assumed to be "undefined" and
     no special processing is attempted.  Legal values are
     "7BIT" and "8BITMIME".

Z    The original envelope id (from the ESMTP transaction).
     For Deliver Status Notifications only.

     As an example, the following is a queue file sent to
"eric@mammoth.Berkeley.EDU" and
"bostic@okeeffe.CS.Berkeley.EDU"[1]:

    V4
    T711358135
    K904446490
    N0
    P2100941
    $_eric@localhost
    ${daemon_flags}
    Seric
    Ceric:100:1000:sendmail@vangogh.CS.Berkeley.EDU
    RPFD:eric@mammoth.Berkeley.EDU
    RPFD:bostic@okeeffe.CS.Berkeley.EDU
    H?P?Return-path: <^g>
    H??Received: by vangogh.CS.Berkeley.EDU (5.108/2.7) id AAA06703;
        Fri, 17 Jul 1992 00:28:55 -0700
    H??Received: from mail.CS.Berkeley.EDU by vangogh.CS.Berkeley.EDU (5.108/2.7)
        id AAA06698; Fri, 17 Jul 1992 00:28:54 -0700
    H??Received: from [128.32.31.21] by mail.CS.Berkeley.EDU (5.96/2.5)
        id AA22777; Fri, 17 Jul 1992 03:29:14 -0400
    H??Received: by foo.bar.baz.de (5.57/Ultrix3.0-C)
        id AA22757; Fri, 17 Jul 1992 09:31:25 GMT
    H?F?From: eric@foo.bar.baz.de (Eric Allman)
    H?x?Full-name: Eric Allman
    H??Message-id: <9207170931.AA22757@foo.bar.baz.de>
    H??To: sendmail@vangogh.CS.Berkeley.EDU
    H??Subject: this is an example message

This shows the person who sent the message, the submission
time (in seconds since January 1, 1970), the message
priority, the message class, the recipients, and the headers
for the message.

____________________
   [1]This  example is contrived and probably inaccurate for
your environment.  Glance over it to get  an  idea;  nothing
can replace looking at what your own system generates.















                        APPENDIX  C


                  SUMMARY OF SUPPORT FILES




     This is a summary of the support files that sendmail
creates or generates.  Many of these can be changed by
editing the sendmail.cf file; check there to find the actual
pathnames.

/usr/sbin/sendmail
          The binary of sendmail.

/usr/bin/newaliases
          A link to /usr/sbin/sendmail; causes the alias
          database to be rebuilt.  Running this program is
          completely equivalent to giving sendmail the -bi
          flag.

/usr/bin/mailq
          Prints a listing of the mail queue.  This program
          is equivalent to using the -bp flag to sendmail.

/etc/mail/sendmail.cf
          The configuration file, in textual form.

/etc/mail/helpfile
          The SMTP help file.

/etc/mail/statistics
          A statistics file; need not be present.

/etc/mail/sendmail.pid
          Created in daemon mode; it contains the process id
          of the current SMTP daemon.  If you use this in
          scripts; use ``head -1'' to get just the first
          line; the second line contains the command line
          used to invoke the daemon, and later versions of
          sendmail may add more information to subsequent
          lines.

/etc/mail/aliases
          The textual version of the alias file.

/etc/mail/aliases.db
          The alias file in hash(3) format.

/etc/mail/aliases.{pag,dir}
          The alias file in ndbm(3) format.



Sendmail Installation and Operation Guide         SMM:08-181







SMM:08-182         Sendmail Installation and Operation Guide


/var/spool/mqueue
          The directory in which the mail queue(s) and
          temporary files reside.

/var/spool/mqueue/qf*
          Control (queue) files for messages.

/var/spool/mqueue/df*
          Data files.

/var/spool/mqueue/tf*
          Temporary versions of the qf files, used during
          queue file rebuild.

/var/spool/mqueue/xf*
          A transcript of the current session.















































Sendmail Installation and Operation Guide           SMM:08-3


                          TABLE OF CONTENTS

1.  BASIC INSTALLATION ................................    7
   1.1.  Compiling Sendmail ...........................    7
      1.1.1.  Tweaking the Build Invocation ...........    7
      1.1.2.  Creating a Site Configuration File ......    8
      1.1.3.  Tweaking the Makefile ...................    8
      1.1.4.  Compilation and installation ............    9
   1.2.  Configuration Files ..........................   10
   1.3.  Details of Installation Files ................   12
      1.3.1.  /usr/sbin/sendmail ......................   12
      1.3.2.  /etc/mail/sendmail.cf ...................   12
      1.3.3.  /etc/mail/submit.cf .....................   13
      1.3.4.  /usr/bin/newaliases .....................   13
      1.3.5.  /usr/bin/hoststat .......................   13
      1.3.6.  /usr/bin/purgestat ......................   13
      1.3.7.  /var/spool/mqueue .......................   14
      1.3.8.  /var/spool/clientmqueue .................   14
      1.3.9.  /var/spool/mqueue/.hoststat .............   15
      1.3.10.  /etc/mail/aliases* .....................   15
      1.3.11.  /etc/rc or /etc/init.d/sendmail ........   15
      1.3.12.  /etc/mail/helpfile .....................   16
      1.3.13.  /etc/mail/statistics ...................   16
      1.3.14.  /usr/bin/mailq .........................   16
      1.3.15.  sendmail.pid ...........................   18
      1.3.16.  Map Files ..............................   18
2.  NORMAL OPERATIONS .................................   19
   2.1.  The System Log ...............................   19
      2.1.1.  Format ..................................   19
      2.1.2.  Levels ..................................   20
   2.2.  Dumping State ................................   21
   2.3.  The Mail Queues ..............................   21
      2.3.1.  Queue Groups and Queue Directories ......   21
      2.3.2.  Queue Runs ..............................   22
      2.3.3.  Manual Intervention .....................   23
      2.3.4.  Printing the queue ......................   23
      2.3.5.  Forcing the queue .......................   24
      2.3.6.  Quarantined Queue Items .................   25
   2.4.  Disk Based Connection Information ............   26
   2.5.  The Service Switch ...........................   27
   2.6.  The Alias Database ...........................   28
      2.6.1.  Rebuilding the alias database ...........   30
      2.6.2.  Potential problems ......................   30
      2.6.3.  List owners .............................   31
   2.7.  User Information Database ....................   31
   2.8.  Per-User Forwarding (.forward Files) .........   32
   2.9.  Special Header Lines .........................   32
      2.9.1.  Errors-To: ..............................   32
      2.9.2.  Apparently-To: ..........................   33
      2.9.3.  Precedence ..............................   33
   2.10.  IDENT Protocol Support ......................   33
3.  ARGUMENTS .........................................   34
   3.1.  Queue Interval ...............................   34










SMM:08-4           Sendmail Installation and Operation Guide


   3.2.  Daemon Mode ..................................   35
   3.3.  Forcing the Queue ............................   35
   3.4.  Debugging ....................................   36
   3.5.  Changing the Values of Options ...............   37
   3.6.  Trying a Different Configuration File ........   37
   3.7.  Logging Traffic ..............................   38
   3.8.  Testing Configuration Files ..................   38
   3.9.  Persistent Host Status Information ...........   40
4.  TUNING ............................................   40
   4.1.  Timeouts .....................................   41
      4.1.1.  Queue interval ..........................   41
      4.1.2.  Read timeouts ...........................   41
      4.1.3.  Message timeouts ........................   44
   4.2.  Forking During Queue Runs ....................   46
   4.3.  Queue Priorities .............................   46
   4.4.  Load Limiting ................................   47
   4.5.  Resource Limits ..............................   47
   4.6.   Measures against Denial of Service Attacks
      .................................................   48
   4.7.  Delivery Mode ................................   48
   4.8.  Log Level ....................................   49
   4.9.  File Modes ...................................   50
      4.9.1.  To suid or not to suid?  ................   50
      4.9.2.  Turning off security checks .............   51
   4.10.  Connection Caching ..........................   55
   4.11.  Name Server Access ..........................   55
   4.12.  Moving the Per-User Forward Files ...........   57
   4.13.  Free Space ..................................   58
   4.14.  Maximum Message Size ........................   58
   4.15.  Privacy Flags ...............................   58
   4.16.  Send to Me Too ..............................   59
5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE .........   59
   5.1.  R and S -- Rewriting Rules ...................   59
      5.1.1.  The left hand side ......................   60
      5.1.2.  The right hand side .....................   61
      5.1.3.  Semantics of rewriting rule sets ........   63
      5.1.4.  Ruleset hooks ...........................   64
         5.1.4.1.  check_relay ........................   65
         5.1.4.2.  check_mail .........................   65
         5.1.4.3.  check_rcpt .........................   65
         5.1.4.4.  check_data .........................   65
         5.1.4.5.  check_compat .......................   66
         5.1.4.6.  check_eoh ..........................   66
         5.1.4.7.  check_eom ..........................   67
         5.1.4.8.  check_etrn .........................   67
         5.1.4.9.  check_expn .........................   67
         5.1.4.10.  check_vrfy ........................   67
         5.1.4.11.  trust_auth ........................   67
         5.1.4.12.  tls_client ........................   67
         5.1.4.13.  tls_server ........................   68
         5.1.4.14.  tls_rcpt ..........................   68
         5.1.4.15.  srv_features ......................   68
         5.1.4.16.  try_tls ...........................   69










Sendmail Installation and Operation Guide           SMM:08-5


         5.1.4.17.        tls_srv_features       and
            tls_clt_features
                 ......................................   69
         5.1.4.18.  authinfo ..........................   71
         5.1.4.19.  queuegroup ........................   71
         5.1.4.20.  greet_pause .......................   71
      5.1.5.  IPC mailers .............................   72
   5.2.  D -- Define Macro ............................   73
   5.3.  C and F -- Define Classes ....................   84
   5.4.  M -- Define Mailer ...........................   87
   5.5.  H -- Define Header ...........................   95
   5.6.  O -- Set Option ..............................   97
   5.7.  P -- Precedence Definitions ..................  131
   5.8.  V -- Configuration Version Level .............  132
   5.9.  K -- Key File Declaration ....................  134
   5.10.  Q -- Queue Group Declaration ................  147
   5.11.  X -- Mail Filter (Milter) Definitions .......  149
   5.12.  The User Database ...........................  151
      5.12.1.  Structure of the user database .........  151
      5.12.2.  User database semantics ................  152
      5.12.3.  Creating the database[23] ..............  153
6.  OTHER CONFIGURATION ...............................  154
   6.1.  Parameters in devtools/OS/$oscf ..............  154
      6.1.1.  For Future Releases .....................  155
   6.2.  Parameters in sendmail/conf.h ................  156
   6.3.  Configuration in sendmail/conf.c .............  160
      6.3.1.  Built-in Header Semantics ...............  160
      6.3.2.  Restricting Use of Email ................  163
      6.3.3.  New Database Map Classes ................  164
      6.3.4.  Queueing Function .......................  164
      6.3.5.  Refusing Incoming SMTP Connections ......  165
      6.3.6.  Load Average Computation ................  166
   6.4.  Configuration in sendmail/daemon.c ...........  166
   6.5.  LDAP .........................................  166
      6.5.1.  LDAP Recursion ..........................  166
         6.5.1.1.  Example ............................  167
   6.6.  STARTTLS .....................................  168
      6.6.1.  Certificates for STARTTLS ...............  168
      6.6.2.  PRNG for STARTTLS .......................  169
   6.7.   Encoding  of  STARTTLS  and  AUTH  related
      Macros ..........................................  170
   6.8.  DANE .........................................  170
7.  ACKNOWLEDGEMENTS ..................................  171
Appendix A.  COMMAND LINE FLAGS .......................  173
Appendix B.  QUEUE FILE FORMATS .......................  177
Appendix C.  SUMMARY OF SUPPORT FILES .................  181

















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