Postfix manual - pipe(8)

    PIPE(8)                                                                PIPE(8)

    NAME
           pipe - Postfix delivery to external command

    SYNOPSIS
           pipe [generic Postfix daemon options] command_attributes...

    DESCRIPTION
           The  pipe(8)  daemon  processes  requests from the Postfix
           queue manager to deliver messages  to  external  commands.
           This  program expects to be run from the master(8) process
           manager.

           Message  attributes  such  as  sender  address,  recipient
           address  and  next-hop  host name can be specified as com-
           mand-line macros that are  expanded  before  the  external
           command is executed.

           The  pipe(8)  daemon updates queue files and marks recipi-
           ents as finished, or it informs  the  queue  manager  that
           delivery  should  be tried again at a later time. Delivery
           status reports are sent  to  the  bounce(8),  defer(8)  or
           trace(8) daemon as appropriate.

    SINGLE-RECIPIENT DELIVERY
           Some  destinations  cannot  handle more than one recipient
           per delivery request. Examples are pagers or fax machines.
           In  addition, multi-recipient delivery is undesirable when
           prepending  a  Delivered-to:  or  X-Original-To:   message
           header.

           To  prevent  Postfix  from sending multiple recipients per
           delivery request, specify

               transport_destination_recipient_limit = 1

           in the Postfix main.cf file, where transport is  the  name
           in the first column of the Postfix master.cf entry for the
           pipe-based delivery transport.

    COMMAND ATTRIBUTE SYNTAX
           The external command attributes are given in the master.cf
           file at the end of a service definition.  The syntax is as
           follows:

           chroot=pathname (optional)
                  Change  the  process  root  directory  and  working
                  directory  to  the  named  directory.  This happens
                  before switching to the privileges  specified  with
                  the   user  attribute,  and  before  executing  the
                  optional directory=pathname directive. Delivery  is
                  deferred in case of failure.

                  This feature is available as of Postfix 2.3.

           directory=pathname (optional)
                  Change  to the named directory before executing the
                  external command.  The directory must be accessible
                  for the user specified with the user attribute (see
                  below).    The   default   working   directory   is
                  $queue_directory.   Delivery is deferred in case of
                  failure.

                  This feature is available as of Postfix 2.2.

           eol=string (optional, default: \n)
                  The output record delimiter.  Typically  one  would
                  use  either \r\n or \n. The usual C-style backslash
                  escape sequences are recognized: \a \b \f \n \r  \t
                  \v \ddd (up to three octal digits) and \\.

           flags=BDFORXhqu.> (optional)
                  Optional  message  processing  flags. By default, a
                  message is copied unchanged.

                  B      Append a blank line at the end of each  mes-
                         sage.  This  is  required  by some mail user
                         agents that recognize  "From  "  lines  only
                         when preceded by a blank line.

                  D      Prepend  a "Delivered-To: recipient" message
                         header with the envelope recipient  address.
                         Note: for this to work, the transport_desti-
                         nation_recipient_limit must be 1  (see  SIN-
                         GLE-RECIPIENT DELIVERY above for details).

                         The  D  flag  also  enforces  loop detection
                         (Postfix  2.5  and  later):  if  a   message
                         already contains a Delivered-To: header with
                         the same recipient address, then the message
                         is  returned  as  undeliverable. The address
                         comparison is case insensitive.

                         This feature is available as of Postfix 2.0.

                  F      Prepend  a "From sender time_stamp" envelope
                         header to  the  message  content.   This  is
                         expected by, for example, UUCP software.

                  O      Prepend  an  "X-Original-To: recipient" mes-
                         sage header with the  recipient  address  as
                         given  to  Postfix.  Note: for this to work,
                         the    transport_destination_recipient_limit
                         must  be  1  (see  SINGLE-RECIPIENT DELIVERY
                         above for details).

                         This feature is available as of Postfix 2.0.

                  R      Prepend  a  Return-Path: message header with
                         the envelope sender address.

                  X      Indicate that the external command  performs
                         final  delivery.  This flag affects the sta-
                         tus reported in "success" DSN (delivery sta-
                         tus  notification)  messages, and changes it
                         from "relayed" into "delivered".

                         This feature is available as of Postfix 2.5.

                  h      Fold  the  command-line  $original_recipient
                         and $recipient address domain part (text  to
                         the  right of the right-most @ character) to
                         lower case;  fold  the  entire  command-line
                         $domain and $nexthop host or domain informa-
                         tion to lower case.  This is recommended for
                         delivery via UUCP.

                  q      Quote  white space and other special charac-
                         ters in the  command-line  $sender,  $origi-
                         nal_recipient  and $recipient address local-
                         parts (text to the left of the right-most  @
                         character),  according to an 8-bit transpar-
                         ent version of RFC 822.  This is recommended
                         for delivery via UUCP or BSMTP.

                         The  result  is  compatible with the address
                         parsing of command-line  recipients  by  the
                         Postfix sendmail(1) mail submission command.

                         The q flag affects  only  entire  addresses,
                         not the partial address information from the
                         $user, $extension or  $mailbox  command-line
                         macros.

                  u      Fold  the  command-line  $original_recipient
                         and $recipient address  localpart  (text  to
                         the  left  of the right-most @ character) to
                         lower case.  This is recommended for  deliv-
                         ery via UUCP.

                  .      Prepend "." to lines starting with ".". This
                         is needed by, for example, BSMTP software.

                  >      Prepend ">" to lines starting with "From  ".
                         This is expected by, for example, UUCP soft-
                         ware.

           null_sender=replacement (default: MAILER-DAEMON)
                  Replace the null sender address (typically used for
                  delivery  status  notifications) with the specified
                  text when expanding the $sender command-line macro,
                  and when generating a From_ or Return-Path: message
                  header.

                  If the null sender replacement text is a  non-empty
                  string  then  it  is  affected  by  the  q flag for
                  address quoting in command-line arguments.

                  The null sender replacement text may be empty; this
                  form  is  recommended for content filters that feed
                  mail back into Postfix. The empty sender address is
                  not  affected  by the q flag for address quoting in
                  command-line arguments.

                  Caution: a null sender address is easily mis-parsed
                  by  naive  software.  For example, when the pipe(8)
                  daemon executes a command such as:

                      Wrong: command -f$sender -- $recipient

                  the command will mis-parse the -f option value when
                  the  sender  address is a null string.  For correct
                  parsing, specify $sender as an argument by itself:

                      Right: command -f $sender -- $recipient

                  This feature is available as of Postfix 2.3.

           size=size_limit (optional)
                  Don't deliver messages that exceed this size  limit
                  (in bytes); return them to the sender instead.

           user=username (required)

           user=username:groupname
                  Execute  the  external command with the user ID and
                  group ID of the specified username.   The  software
                  refuses  to  execute commands with root privileges,
                  or with the privileges of the mail system owner. If
                  groupname  is specified, the corresponding group ID
                  is used instead of the group ID of username.

           argv=command... (required)
                  The command to be executed. This must be  specified
                  as the last command attribute.  The command is exe-
                  cuted  directly,  i.e.  without  interpretation  of
                  shell  meta  characters  by  a shell command inter-
                  preter.

                  In  the  command  argument  vector,  the  following
                  macros are recognized and replaced with correspond-
                  ing information  from  the  Postfix  queue  manager
                  delivery request.

                  In  addition  to  the form ${name}, the forms $name
                  and $(name) are also recognized.  Specify $$  where
                  a single $ is wanted.

                  ${client_address}
                         This macro expands to the remote client net-
                         work address.

                         This feature is available as of Postfix 2.2.

                  ${client_helo}
                         This macro expands to the remote client HELO
                         command parameter.

                         This feature is available as of Postfix 2.2.

                  ${client_hostname}
                         This  macro  expands  to  the  remote client
                         hostname.

                         This feature is available as of Postfix 2.2.

                  ${client_port}
                         This  macro expands to the remote client TCP
                         port number.

                         This feature is available as of Postfix 2.5.

                  ${client_protocol}
                         This macro expands to the remote client pro-
                         tocol.

                         This feature is available as of Postfix 2.2.

                  ${domain}
                         This  macro expands to the domain portion of
                         the recipient address.  For example, with an
                         address   user+foo@domain   the   domain  is
                         domain.

                         This information is modified by the  h  flag
                         for case folding.

                         This feature is available as of Postfix 2.5.

                  ${extension}
                         This macro expands to the extension part  of
                         a  recipient  address.  For example, with an
                         address  user+foo@domain  the  extension  is
                         foo.

                         A   command-line   argument   that  contains
                         ${extension} expands into as  many  command-
                         line arguments as there are recipients.

                         This  information  is modified by the u flag
                         for case folding.

                  ${mailbox}
                         This macro expands  to  the  complete  local
                         part  of  a recipient address.  For example,
                         with an address user+foo@domain the  mailbox
                         is user+foo.

                         A   command-line   argument   that  contains
                         ${mailbox} expands to as  many  command-line
                         arguments as there are recipients.

                         This  information  is modified by the u flag
                         for case folding.

                  ${nexthop}
                         This macro expands to the next-hop hostname.

                         This  information  is modified by the h flag
                         for case folding.

                  ${original_recipient}
                         This macro expands to the complete recipient
                         address  before  any  address  rewriting  or
                         aliasing.

                         A  command-line   argument   that   contains
                         ${original_recipient}  expands  to  as  many
                         command-line arguments as there are  recipi-
                         ents.

                         This  information  is  modified  by  the hqu
                         flags for quoting and case folding.

                         This feature is available as of Postfix 2.5.

                  ${recipient}
                         This macro expands to the complete recipient
                         address.

                         A  command-line   argument   that   contains
                         ${recipient} expands to as many command-line
                         arguments as there are recipients.

                         This information  is  modified  by  the  hqu
                         flags for quoting and case folding.

                  ${sasl_method}
                         This  macro  expands to the name of the SASL
                         authentication mechanism in the AUTH command
                         when  the  Postfix  SMTP server received the
                         message.

                         This feature is available as of Postfix 2.2.

                  ${sasl_sender}
                         This  macro  expands to the SASL sender name
                         (i.e. the  original  submitter  as  per  RFC
                         4954)  in  the  MAIL  FROM  command when the
                         Postfix SMTP server received the message.

                         This feature is available as of Postfix 2.2.

                  ${sasl_username}
                         This  macro expands to the SASL user name in
                         the  AUTH  command  when  the  Postfix  SMTP
                         server received the message.

                         This feature is available as of Postfix 2.2.

                  ${sender}
                         This macro expands to  the  envelope  sender
                         address. By default, the null sender address
                         expands  to  MAILER-DAEMON;  this   can   be
                         changed  with  the null_sender attribute, as
                         described above.

                         This information is modified by the  q  flag
                         for quoting.

                  ${size}
                         This  macro expands to Postfix's idea of the
                         message size, which is an  approximation  of
                         the size of the message as delivered.

                  ${user}
                         This macro expands to the username part of a
                         recipient address.   For  example,  with  an
                         address user+foo@domain the username part is
                         user.

                         A  command-line   argument   that   contains
                         ${user}  expands  into  as many command-line
                         arguments as there are recipients.

                         This information is modified by the  u  flag
                         for case folding.

    STANDARDS
           RFC 3463 (Enhanced status codes)

    DIAGNOSTICS
           Command  exit status codes are expected to follow the con-
           ventions defined in <sysexits.h>.   Exit  status  0  means
           normal successful completion.

           In the case of a non-zero exit status, a limited amount of
           command output is reported in an delivery status notifica-
           tion.   When  the  output  begins  with  a  4.X.X or 5.X.X
           enhanced status code, the  status  code  takes  precedence
           over  the  non-zero  exit  status (Postfix version 2.3 and
           later).

           Problems and transactions are logged to syslogd(8).   Cor-
           rupted  message files are marked so that the queue manager
           can move them to the corrupt queue for further inspection.

    SECURITY
           This  program  needs  a  dual personality 1) to access the
           private Postfix queue and IPC mechanisms, and 2)  to  exe-
           cute external commands as the specified user. It is there-
           fore security sensitive.

    CONFIGURATION PARAMETERS
           Changes to main.cf are picked up automatically as  pipe(8)
           processes  run  for only a limited amount of time. Use the
           command "postfix reload" to speed up a change.

           The text below provides  only  a  parameter  summary.  See
           postconf(5) for more details including examples.

    RESOURCE AND RATE CONTROLS
           In  the text below, transport is the first field in a mas-
           ter.cf entry.

           transport_destination_concurrency_limit ($default_destina-
           tion_concurrency_limit)
                  Limit the number of parallel deliveries to the same
                  destination,  for delivery via the named transport.
                  The limit is enforced by the Postfix queue manager.

           transport_destination_recipient_limit   ($default_destina-
           tion_recipient_limit)
                  Limit  the  number of recipients per message deliv-
                  ery, for delivery via  the  named  transport.   The
                  limit is enforced by the Postfix queue manager.

           transport_time_limit ($command_time_limit)
                  Limit  the  time  for delivery to external command,
                  for delivery via the named transport.  The limit is
                  enforced by the pipe delivery agent.

                  Postfix  2.4 and later support a suffix that speci-
                  fies the time unit: s  (seconds),  m  (minutes),  h
                  (hours), d (days), w (weeks). The default time unit
                  is seconds.

    MISCELLANEOUS CONTROLS
           config_directory (see 'postconf -d' output)
                  The default location of  the  Postfix  main.cf  and
                  master.cf configuration files.

           daemon_timeout (18000s)
                  How  much time a Postfix daemon process may take to
                  handle a request  before  it  is  terminated  by  a
                  built-in watchdog timer.

           delay_logging_resolution_limit (2)
                  The  maximal  number  of  digits  after the decimal
                  point when logging sub-second delay values.

           export_environment (see 'postconf -d' output)
                  The list of environment variables  that  a  Postfix
                  process will export to non-Postfix processes.

           ipc_timeout (3600s)
                  The time limit for sending or receiving information
                  over an internal communication channel.

           mail_owner (postfix)
                  The UNIX system account that owns the Postfix queue
                  and most Postfix daemon processes.

           max_idle (100s)
                  The  maximum  amount  of  time that an idle Postfix
                  daemon process waits  for  an  incoming  connection
                  before terminating voluntarily.

           max_use (100)
                  The  maximal  number of incoming connections that a
                  Postfix daemon process will service  before  termi-
                  nating voluntarily.

           process_id (read-only)
                  The  process  ID  of  a  Postfix  command or daemon
                  process.

           process_name (read-only)
                  The process name of a  Postfix  command  or  daemon
                  process.

           queue_directory (see 'postconf -d' output)
                  The  location of the Postfix top-level queue direc-
                  tory.

           recipient_delimiter (empty)
                  The separator between user names and address exten-
                  sions (user+foo).

           syslog_facility (mail)
                  The syslog facility of Postfix logging.

           syslog_name (see 'postconf -d' output)
                  The  mail  system  name  that  is  prepended to the
                  process name in syslog  records,  so  that  "smtpd"
                  becomes, for example, "postfix/smtpd".

    SEE ALSO
           qmgr(8), queue manager
           bounce(8), delivery status reports
           postconf(5), configuration parameters
           master(5), generic daemon options
           master(8), process manager
           syslogd(8), system logging

    LICENSE
           The  Secure  Mailer  license must be distributed with this
           software.

    AUTHOR(S)
           Wietse Venema
           IBM T.J. Watson Research
           P.O. Box 704
           Yorktown Heights, NY 10598, USA

                                                                           PIPE(8)