Postfix manual - local(8)

    LOCAL(8)                                                              LOCAL(8)

    NAME
           local - Postfix local mail delivery

    SYNOPSIS
           local [generic Postfix daemon options]

    DESCRIPTION
           The  local(8) daemon processes delivery requests from the Postfix queue
           manager to deliver mail to local  recipients.   Each  delivery  request
           specifies  a  queue file, a sender address, a domain or host to deliver
           to, and one or more recipients.  This program expects to  be  run  from
           the master(8) process manager.

           The  local(8)  daemon  updates queue files and marks recipients as fin-
           ished, 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.

    CASE FOLDING
           All delivery decisions are made using the bare recipient name (i.e. the
           address  localpart),  folded  to  lower  case.   See also under ADDRESS
           EXTENSION below for a few exceptions.

    SYSTEM-WIDE AND USER-LEVEL ALIASING
           The system administrator can set  up  one  or  more  system-wide  send-
           mail-style  alias  databases.  Users can have sendmail-style ~/.forward
           files.  Mail for name is delivered to the alias name,  to  destinations
           in ~name/.forward, to the mailbox owned by the user name, or it is sent
           back as undeliverable.

           The system administrator can specify a comma/space  separated  list  of
           ~/.forward like files through the forward_path configuration parameter.
           Upon delivery, the local delivery agent tries each pathname in the list
           until a file is found.

           Delivery via ~/.forward files is done with the privileges of the recip-
           ient.  Thus, ~/.forward like files must be readable by  the  recipient,
           and  their  parent directory needs to have "execute" permission for the
           recipient.

           The forward_path parameter is subject to interpolation of $user (recip-
           ient  username),  $home  (recipient  home directory), $shell (recipient
           shell), $recipient (complete recipient address), $extension  (recipient
           address  extension), $domain (recipient domain), $local (entire recipi-
           ent   address   localpart)   and   $recipient_delimiter.   The    forms
           ${name?value}  and  ${name:value}  expand  conditionally  to value when
           $name is (is not) defined.  Characters that may have special meaning to
           the  shell  or  file  system  are replaced by underscores.  The list of
           acceptable characters is specified  with  the  forward_expansion_filter
           configuration parameter.

           An  alias  or ~/.forward file may list any combination of external com-
           mands, destination file names, :include: directives, or mail addresses.
           See  aliases(5)  for a precise description. Each line in a user's .for-
           ward file has the same syntax as the right-hand part of an alias.

           When an address is found in its own alias expansion, delivery  is  made
           to the user instead. When a user is listed in the user's own ~/.forward
           file, delivery is made to the user's mailbox instead.  An empty ~/.for-
           ward file means do not forward mail.

           In  order to prevent the mail system from using up unreasonable amounts
           of memory, input records read from :include: or from  ~/.forward  files
           are broken up into chunks of length line_length_limit.

           While  expanding  aliases,  ~/.forward  files,  and  so on, the program
           attempts to avoid duplicate deliveries. The duplicate_filter_limit con-
           figuration parameter limits the number of remembered recipients.

    MAIL FORWARDING
           For  the  sake  of reliability, forwarded mail is re-submitted as a new
           message, so that each recipient has a separate on-file delivery  status
           record.

           In  order  to  stop  mail  forwarding loops early, the software adds an
           optional  Delivered-To:  header  with  the  final  envelope   recipient
           address.  If  mail  arrives for a recipient that is already listed in a
           Delivered-To: header, the message is bounced.

    MAILBOX DELIVERY
           The default per-user mailbox is a file in the UNIX mail spool directory
           (/var/mail/user or /var/spool/mail/user); the location can be specified
           with the mail_spool_directory configuration parameter. Specify  a  name
           ending in / for qmail-compatible maildir delivery.

           Alternatively,  the  per-user  mailbox can be a file in the user's home
           directory with a name  specified  via  the  home_mailbox  configuration
           parameter. Specify a relative path name. Specify a name ending in / for
           qmail-compatible maildir delivery.

           Mailbox delivery can be delegated to an external command specified with
           the  mailbox_command_maps and mailbox_command configuration parameters.
           The command executes with the privileges of the recipient user  (excep-
           tions:  secondary  groups are not enabled; in case of delivery as root,
           the command executes with the privileges of default_privs).

           Mailbox delivery can be delegated  to  alternative  message  transports
           specified  in the master.cf file.  The mailbox_transport_maps and mail-
           box_transport configuration  parameters  specify  an  optional  message
           transport  that  is  to be used for all local recipients, regardless of
           whether they  are  found  in  the  UNIX  passwd  database.   The  fall-
           back_transport_maps   and   fallback_transport  parameters  specify  an
           optional message transport for recipients that are  not  found  in  the
           aliases(5) or UNIX passwd database.

           In  the  case  of  UNIX-style  mailbox  delivery,  the  local(8) daemon
           prepends a "From sender time_stamp" envelope header  to  each  message,
           prepends  an  X-Original-To: header with the recipient address as given
           to Postfix, prepends an optional Delivered-To: header  with  the  final
           envelope  recipient  address,  prepends  a Return-Path: header with the
           envelope sender address, prepends a > character to lines beginning with
           "From  ",  and appends an empty line.  The mailbox is locked for exclu-
           sive access while delivery is in progress.  In  case  of  problems,  an
           attempt is made to truncate the mailbox to its original length.

           In  the case of maildir delivery, the local daemon prepends an optional
           Delivered-To:  header  with  the  final  envelope  recipient   address,
           prepends  an  X-Original-To: header with the recipient address as given
           to Postfix, and prepends a Return-Path: header with the envelope sender
           address.

    EXTERNAL COMMAND DELIVERY
           The  allow_mail_to_commands  configuration parameter restricts delivery
           to external commands. The default setting (alias, forward) forbids com-
           mand destinations in :include: files.

           Optionally, the process working directory is changed to the path speci-
           fied with command_execution_directory (Postfix 2.2 and later).  Failure
           to change directory causes mail to be deferred.

           The  command_execution_directory parameter value is subject to interpo-
           lation of $user (recipient username), $home (recipient home directory),
           $shell  (recipient  shell),  $recipient  (complete  recipient address),
           $extension (recipient address extension), $domain  (recipient  domain),
           $local  (entire  recipient address localpart) and $recipient_delimiter.
           The forms ${name?value} and ${name:value} expand conditionally to value
           when $name is (is not) defined.  Characters that may have special mean-
           ing to the shell or file system are replaced by underscores.  The  list
           of   acceptable  characters  is  specified  with  the  execution_direc-
           tory_expansion_filter configuration parameter.

           The command is executed directly  where  possible.  Assistance  by  the
           shell  (/bin/sh on UNIX systems) is used only when the command contains
           shell magic characters, or when the command invokes  a  shell  built-in
           command.

           A limited amount of command output (standard output and standard error)
           is captured for inclusion with non-delivery status reports.  A  command
           is   forcibly   terminated   if   it  does  not  complete  within  com-
           mand_time_limit seconds.  Command exit status  codes  are  expected  to
           follow  the  conventions  defined in <sysexits.h>.  Exit status 0 means
           normal successful completion.

           Postfix version 2.3 and later support RFC  3463-style  enhanced  status
           codes.   If  a  command terminates with a non-zero exit status, and the
           command output begins with an enhanced status code,  this  status  code
           takes precedence over the non-zero exit status.

           A  limited  amount of message context is exported via environment vari-
           ables. Characters that may  have  special  meaning  to  the  shell  are
           replaced  by  underscores.  The list of acceptable characters is speci-
           fied with the command_expansion_filter configuration parameter.

           SHELL  The recipient user's login shell.

           HOME   The recipient user's home directory.

           USER   The bare recipient name.

           EXTENSION
                  The optional recipient address extension.

           DOMAIN The recipient address domain part.

           LOGNAME
                  The bare recipient name.

           LOCAL  The entire recipient address localpart (text to the left of  the
                  rightmost @ character).

           ORIGINAL_RECIPIENT
                  The  entire  recipient  address, before any address rewriting or
                  aliasing (Postfix 2.5 and later).

           RECIPIENT
                  The entire recipient address.

           SENDER The entire sender address.

           Additional remote client information is made available via the  follow-
           ing environment variables:

           CLIENT_ADDRESS
                  Remote client network address. Available as of Postfix 2.2.

           CLIENT_HELO
                  Remote  client  EHLO  command parameter. Available as of Postfix
                  2.2.

           CLIENT_HOSTNAME
                  Remote client hostname. Available as of Postfix 2.2.

           CLIENT_PROTOCOL
                  Remote client protocol. Available as of Postfix 2.2.

           SASL_METHOD
                  SASL authentication method specified in the remote  client  AUTH
                  command. Available as of Postfix 2.2.

           SASL_SENDER
                  SASL  sender  address  specified  in the remote client MAIL FROM
                  command. Available as of Postfix 2.2.

           SASL_USERNAME
                  SASL username specified  in  the  remote  client  AUTH  command.
                  Available as of Postfix 2.2.

           The  PATH  environment  variable  is always reset to a system-dependent
           default path, and environment variables whose names are blessed by  the
           export_environment configuration parameter are exported unchanged.

           The current working directory is the mail queue directory.

           The local(8) daemon prepends a "From sender time_stamp" envelope header
           to each message, prepends an X-Original-To: header with  the  recipient
           address  as given to Postfix, prepends an optional Delivered-To: header
           with the final recipient  envelope  address,  prepends  a  Return-Path:
           header with the sender envelope address, and appends no empty line.

    EXTERNAL FILE DELIVERY
           The  delivery  format  depends on the destination filename syntax.  The
           default is to use UNIX-style mailbox format.  Specify a name ending  in
           / for qmail-compatible maildir delivery.

           The  allow_mail_to_files  configuration parameter restricts delivery to
           external files. The default setting (alias, forward) forbids file  des-
           tinations in :include: files.

           In  the  case  of  UNIX-style  mailbox  delivery,  the  local(8) daemon
           prepends a "From sender time_stamp" envelope header  to  each  message,
           prepends  an  X-Original-To: header with the recipient address as given
           to Postfix, prepends an optional Delivered-To: header  with  the  final
           recipient  envelope  address, prepends a > character to lines beginning
           with "From ", and appends an empty line.  The envelope  sender  address
           is  available  in  the  Return-Path: header.  When the destination is a
           regular file, it is locked for exclusive access while  delivery  is  in
           progress. In case of problems, an attempt is made to truncate a regular
           file to its original length.

           In the case of maildir delivery, the local daemon prepends an  optional
           Delivered-To:  header  with  the  final envelope recipient address, and
           prepends an X-Original-To: header with the recipient address  as  given
           to   Postfix.    The  envelope  sender  address  is  available  in  the
           Return-Path: header.

    ADDRESS EXTENSION
           The optional recipient_delimiter configuration parameter specifies  how
           to separate address extensions from local recipient names.

           For  example,  with  "recipient_delimiter  =  +",  mail for name+foo is
           delivered to the alias name+foo or to the alias name, to  the  destina-
           tions listed in ~name/.forward+foo or in ~name/.forward, to the mailbox
           owned by the user name, or it is sent back as undeliverable.

    DELIVERY RIGHTS
           Deliveries to external files and external commands are  made  with  the
           rights  of the receiving user on whose behalf the delivery is made.  In
           the absence of a user context,  the  local(8)  daemon  uses  the  owner
           rights  of  the :include: file or alias database.  When those files are
           owned by the superuser, delivery is made with the rights specified with
           the default_privs configuration parameter.

    STANDARDS
           RFC 822 (ARPA Internet Text Messages)
           RFC 3463 (Enhanced status codes)

    DIAGNOSTICS
           Problems  and transactions are logged to syslogd(8).  Corrupted message
           files are marked so that the queue manager can move them to the corrupt
           queue afterwards.

           Depending  on the setting of the notify_classes parameter, the postmas-
           ter is notified of bounces and of other trouble.

    SECURITY
           The local(8) delivery agent needs a dual personality 1) to  access  the
           private Postfix queue and IPC mechanisms, 2) to impersonate the recipi-
           ent and deliver to recipient-specified files or commands. It is  there-
           fore security sensitive.

           The  local(8)  delivery agent disallows regular expression substitution
           of $1 etc. in alias_maps, because that would open a security hole.

           The local(8) delivery agent will silently ignore requests  to  use  the
           proxymap(8)  server  within  alias_maps. Instead it will open the table
           directly.  Before Postfix version 2.2, the local(8) delivery agent will
           terminate with a fatal error.

    BUGS
           For  security reasons, the message delivery status of external commands
           or of external files is never checkpointed to file. As  a  result,  the
           program  may occasionally deliver more than once to a command or exter-
           nal file. Better safe than sorry.

           Mutually-recursive aliases or ~/.forward files are not detected  early.
           The  resulting  mail forwarding loop is broken by the use of the Deliv-
           ered-To: message header.

    CONFIGURATION PARAMETERS
           Changes to main.cf are picked up automatically, as  local(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.

    COMPATIBILITY CONTROLS
           biff (yes)
                  Whether or not to use the local biff service.

           expand_owner_alias (no)
                  When   delivering   to   an   alias   "aliasname"  that  has  an
                  "owner-aliasname"  companion  alias,  set  the  envelope  sender
                  address to the expansion of the "owner-aliasname" alias.

           owner_request_special (yes)
                  Enable  special  treatment  for  owner-listname  entries  in the
                  aliases(5)  file,  and  don't  split  owner-listname  and  list-
                  name-request  address localparts when the recipient_delimiter is
                  set to "-".

           sun_mailtool_compatibility (no)
                  Obsolete SUN mailtool compatibility feature.

           Available in Postfix version 2.3 and later:

           frozen_delivered_to (yes)
                  Update the local(8) delivery agent's idea of  the  Delivered-To:
                  address  (see  prepend_delivered_header) only once, at the start
                  of a delivery attempt; do not update the  Delivered-To:  address
                  while expanding aliases or .forward files.

           Available in Postfix version 2.5.3 and later:

           strict_mailbox_ownership (yes)
                  Defer  delivery  when a mailbox file is not owned by its recipi-
                  ent.

           reset_owner_alias (no)
                  Reset the local(8) delivery  agent's  idea  of  the  owner-alias
                  attribute,  when  delivering mail to a child alias that does not
                  have its own owner alias.

           Available in Postfix version 3.0 and later:

           local_delivery_status_filter ($default_delivery_status_filter)
                  Optional filter for the local(8) delivery agent  to  change  the
                  status  code  or  explanatory text of successful or unsuccessful
                  deliveries.

    DELIVERY METHOD CONTROLS
           The precedence of local(8)  delivery  methods  from  high  to  low  is:
           aliases,  .forward  files,  mailbox_transport_maps,  mailbox_transport,
           mailbox_command_maps, mailbox_command, home_mailbox,  mail_spool_direc-
           tory, fallback_transport_maps, fallback_transport, and luser_relay.

           alias_maps (see 'postconf -d' output)
                  The alias databases that are used for local(8) delivery.

           forward_path (see 'postconf -d' output)
                  The  local(8)  delivery agent search list for finding a .forward
                  file with user-specified delivery methods.

           mailbox_transport_maps (empty)
                  Optional  lookup  tables  with  per-recipient  message  delivery
                  transports  to use for local(8) mailbox delivery, whether or not
                  the recipients are found in the UNIX passwd database.

           mailbox_transport (empty)
                  Optional message delivery transport that the  local(8)  delivery
                  agent  should  use for mailbox delivery to all local recipients,
                  whether or not they are found in the UNIX passwd database.

           mailbox_command_maps (empty)
                  Optional lookup tables with per-recipient external  commands  to
                  use for local(8) mailbox delivery.

           mailbox_command (empty)
                  Optional  external  command  that  the  local(8)  delivery agent
                  should use for mailbox delivery.

           home_mailbox (empty)
                  Optional pathname of a  mailbox  file  relative  to  a  local(8)
                  user's home directory.

           mail_spool_directory (see 'postconf -d' output)
                  The directory where local(8) UNIX-style mailboxes are kept.

           fallback_transport_maps (empty)
                  Optional  lookup  tables  with  per-recipient  message  delivery
                  transports for recipients that the local(8) delivery agent could
                  not find in the aliases(5) or UNIX password database.

           fallback_transport (empty)
                  Optional  message  delivery transport that the local(8) delivery
                  agent should use for names that are not found in the  aliases(5)
                  or UNIX password database.

           luser_relay (empty)
                  Optional  catch-all destination for unknown local(8) recipients.

           Available in Postfix version 2.2 and later:

           command_execution_directory (empty)
                  The local(8) delivery agent working directory  for  delivery  to
                  external command.

    MAILBOX LOCKING CONTROLS
           deliver_lock_attempts (20)
                  The maximal number of attempts to acquire an exclusive lock on a
                  mailbox file or bounce(8) logfile.

           deliver_lock_delay (1s)
                  The time between attempts to acquire  an  exclusive  lock  on  a
                  mailbox file or bounce(8) logfile.

           stale_lock_time (500s)
                  The  time  after  which  a  stale  exclusive mailbox lockfile is
                  removed.

           mailbox_delivery_lock (see 'postconf -d' output)
                  How to lock a  UNIX-style  local(8)  mailbox  before  attempting
                  delivery.

    RESOURCE AND RATE CONTROLS
           command_time_limit (1000s)
                  Time limit for delivery to external commands.

           duplicate_filter_limit (1000)
                  The maximal number of addresses remembered by the address dupli-
                  cate filter for aliases(5) or virtual(5) alias expansion, or for
                  showq(8) queue displays.

           mailbox_size_limit (51200000)
                  The  maximal  size of any local(8) individual mailbox or maildir
                  file, or zero (no limit).

           Implemented in the qmgr(8) daemon:

           local_destination_concurrency_limit (2)
                  The maximal number of parallel deliveries  via  the  local  mail
                  delivery  transport  to the same recipient (when "local_destina-
                  tion_recipient_limit = 1") or the  maximal  number  of  parallel
                  deliveries  to  the  same  local  domain  (when  "local_destina-
                  tion_recipient_limit > 1").

           local_destination_recipient_limit (1)
                  The maximal number of recipients per message  delivery  via  the
                  local mail delivery transport.

    SECURITY CONTROLS
           allow_mail_to_commands (alias, forward)
                  Restrict local(8) mail delivery to external commands.

           allow_mail_to_files (alias, forward)
                  Restrict local(8) mail delivery to external files.

           command_expansion_filter (see 'postconf -d' output)
                  Restrict  the characters that the local(8) delivery agent allows
                  in $name  expansions  of  $mailbox_command  and  $command_execu-
                  tion_directory.

           default_privs (nobody)
                  The  default  rights  used  by  the  local(8) delivery agent for
                  delivery to external file or command.

           forward_expansion_filter (see 'postconf -d' output)
                  Restrict the characters that the local(8) delivery agent  allows
                  in $name expansions of $forward_path.

           Available in Postfix version 2.2 and later:

           execution_directory_expansion_filter (see 'postconf -d' output)
                  Restrict  the characters that the local(8) delivery agent allows
                  in $name expansions of $command_execution_directory.

           Available in Postfix version 2.5.3 and later:

           strict_mailbox_ownership (yes)
                  Defer delivery when a mailbox file is not owned by  its  recipi-
                  ent.

    MISCELLANEOUS CONTROLS
           config_directory (see 'postconf -d' output)
                  The  default  location of the Postfix main.cf and master.cf con-
                  figuration 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 log-
                  ging 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.

           local_command_shell (empty)
                  Optional shell program for local(8) delivery to non-Postfix com-
                  mand.

           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 terminating voluntarily.

           prepend_delivered_header (command, file, forward)
                  The message delivery contexts where the Postfix local(8)  deliv-
                  ery  agent  prepends  a  Delivered-To:   message header with the
                  address that the mail was delivered to.

           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.

           propagate_unmatched_extensions (canonical, virtual)
                  What address lookup tables copy an address  extension  from  the
                  lookup key to the lookup result.

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

           recipient_delimiter (empty)
                  The  set  of  characters  that can separate a user name from its
                  extension (example: user+foo), or a .forward file name from  its
                  extension (example: .forward+foo).

           require_home_directory (no)
                  Require that a local(8) recipient's home directory exists before
                  mail delivery is attempted.

           syslog_facility (mail)
                  The syslog facility of Postfix logging.

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

           Available in Postfix version 3.3 and later:

           enable_original_recipient (yes)
                  Enable  support  for  the  original  recipient  address after an
                  address is rewritten to a different address  (for  example  with
                  aliasing or with canonical mapping).

           service_name (read-only)
                  The master.cf service name of a Postfix daemon process.

    FILES
           The following are examples; details differ between systems.
           $HOME/.forward, per-user aliasing
           /etc/aliases, system-wide alias database
           /var/spool/mail, system mailboxes

    SEE ALSO
           qmgr(8), queue manager
           bounce(8), delivery status reports
           newaliases(1), create/update alias database
           postalias(1), create/update alias database
           aliases(5), format of alias database
           postconf(5), configuration parameters
           master(5), generic daemon options
           syslogd(8), system logging

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

    HISTORY
           The  Delivered-To: message header appears in the qmail system by Daniel
           Bernstein.

           The maildir structure appears in the qmail system by Daniel  Bernstein.

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

           Wietse Venema
           Google, Inc.
           111 8th Avenue
           New York, NY 10011, USA

                                                                          LOCAL(8)