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LOCAL(8)                    System Manager's Manual                   LOCAL(8)



NAME
       local - Postfix local mail delivery

SYNOPSIS
       local [generic Postfix daemon options]

DESCRIPTION
       The  local  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 daemon updates queue files and marks recipients as finished,
       or it informs the queue manager that delivery should be tried again  at
       a  later  time.  Delivery  problem reports are sent to the bounce(8) or
       defer(8) daemon as appropriate.

SYSTEM-WIDE AND USER-LEVEL ALIASING
       The system administrator can set up one or more  system-wide  sendmail-
       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.  The forward_path parameter is subject to inter-
       polation of $user (recipient username), $home  (recipient  home  direc-
       tory),   $shell   (recipient  shell),  $recipient  (complete  recipient
       address), $extension (recipient address extension), $domain  (recipient
       domain),  local  (entire  recipient  address  localpart)  and  $recipi-
       ent_delimiter. The forms ${name?value} and ${name:value} expand  condi-
       tionally  to value when $name is (is not) defined.  Characters that may
       have special meaning to the shell or file system are replaced by under-
       scores.   The  list of acceptable characters is specified with the for-
       ward_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 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 configuration parameter. The command executes  with
       the privileges of the recipient user (exception: 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 configuration
       parameter specifies a message transport that is  to  be  used  for  all
       local  recipients,  regardless  of  whether  they are found in the UNIX
       passwd database.  The fallback_transport parameter specifies a  message
       transport  for  recipients  that are not found in the UNIX passwd data-
       base.

       In the case of UNIX-style mailbox delivery, the local 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 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  exclusive  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.

       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>.

       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).

       RECIPIENT
              The entire recipient address.

       SENDER The entire sender address.

       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 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 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 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  recipient  envelope
       address,  prepends  a  >&gt; 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 envelope recipient address, and prepends
       an X-Original-To: header with the recipient address as given  to  Post-
       fix.   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.

       In all cases the  local  daemon  prepends  an  optional  `Delivered-To:
       name+foo' header line.

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 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)

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.

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
       The following main.cf parameters are especially relevant to  this  pro-
       gram.  See  the Postfix main.cf file for syntax details and for default
       values. Use the postfix reload command after a configuration change.

Miscellaneous
       alias_maps
              List of alias databases.

       biff   Enable or disable notification of new mail via the  comsat  net-
              work service.

       expand_owner_alias
              When  delivering to an alias that has an owner- companion alias,
              set the envelope sender address to the right-hand  side  of  the
              owner alias, instead using of the left-hand side address.

       export_environment
              List  of names of environment parameters that can be exported to
              non-Postfix processes.

       forward_path
              Search list for .forward files.  The names are subject to  $name
              expansion.

       local_command_shell
              Shell  to  use  for  external  command  execution  (for example,
              /some/where/smrsh -c).  When a shell is specified, it is invoked
              even  when  the  command  contains no shell built-in commands or
              meta characters.

       owner_request_special
              Give special treatment to owner-xxx and xxx-request addresses.

       prepend_delivered_header
              Prepend an optional Delivered-To: header upon external  forward-
              ing,  delivery to command or file. Specify zero or more of: com-
              mand, file, forward. Turning off Delivered-To:  when  forwarding
              mail is not recommended.

       recipient_delimiter
              Separator between username and address extension.

       require_home_directory
              Require  that  a recipient's home directory is accessible by the
              recipient before attempting delivery. Defer delivery otherwise.

Mailbox delivery
       fallback_transport
              Message transport for recipients that are not found in the  UNIX
              passwd database.  This parameter overrides luser_relay.

              Note:  you  must  update the local_recipient_maps setting in the
              main.cf file, otherwise the Postfix SMTP server will reject mail
              for  non-UNIX accounts with "User unknown in local recipient ta-
              ble".

       home_mailbox
              Pathname of a mailbox  relative  to  a  user's  home  directory.
              Specify a path ending in / for maildir-style delivery.

       luser_relay
              Destination  (@domain  or  address) for non-existent users.  The
              address is subjected to $name expansion.

              Note: you must specify "local_recipient_maps =" (i.e. empty)  in
              the  main.cf file, otherwise the Postfix SMTP server will reject
              mail for non-UNIX accounts with "User unknown in local recipient
              table".

       mail_spool_directory
              Directory  with  UNIX-style  mailboxes.  The default pathname is
              system dependent.  Specify a path ending in / for  maildir-style
              delivery.

       mailbox_command
              External  command  to use for mailbox delivery. The command exe-
              cutes with  the  recipient  privileges  (exception:  root).  The
              string is subject to $name expansions.

       mailbox_command_maps
              Lookup  tables  with  per-recipient external commands to use for
              mailbox delivery. Behavior is as with mailbox_command.

       mailbox_transport
              Message transport to use  for  mailbox  delivery  to  all  local
              recipients,  whether  or  not  they are found in the UNIX passwd
              database.  This  parameter  overrides  all  other  configuration
              parameters that control mailbox delivery, including luser_relay.

              Note:  if  you  use  this  feature  to receive mail for non-UNIX
              accounts then you must update the  local_recipient_maps  setting
              in  the  main.cf  file,  otherwise  the Postfix SMTP server will
              reject mail for non-UNIX accounts with "User  unknown  in  local
              recipient table".

Locking controls
       deliver_lock_attempts
              Limit  the  number of attempts to acquire an exclusive lock on a
              mailbox or external file.

       deliver_lock_delay
              Time in seconds between successive attempts to acquire an exclu-
              sive lock.

       stale_lock_time
              Limit the time after which a stale lock is removed.

       mailbox_delivery_lock
              What  file  locking  method(s) to use when delivering to a UNIX-
              style mailbox.  The default setting is system dependent.  For  a
              list of available file locking methods, use the postconf -l com-
              mand.

Resource controls
       command_time_limit
              Limit the amount of time for delivery to external command.

       duplicate_filter_limit
              Limit the size of the duplicate filter for  results  from  alias
              etc. expansion.

       line_length_limit
              Limit  the  amount of memory used for processing a partial input
              line.

       local_destination_concurrency_limit
              Limit the number of parallel deliveries to the same  user.   The
              default  limit  is  taken  from  the default_destination_concur-
              rency_limit parameter.

       local_destination_recipient_limit
              Limit the  number  of  recipients  per  message  delivery.   The
              default  limit  is  taken  from  the default_destination_recipi-
              ent_limit parameter.

       mailbox_size_limit
              Limit the size of a mailbox etc. file (any file that is  written
              to upon delivery).  Set to zero to disable the limit.

Security controls
       allow_mail_to_commands
              Restrict  the usage of mail delivery to external command.  Spec-
              ify zero or more of: alias, forward, include.

       allow_mail_to_files
              Restrict the usage of mail delivery to external  file.   Specify
              zero or more of: alias, forward, include.

       command_expansion_filter
              What  characters  are  allowed  to appear in $name expansions of
              mailbox_command. Illegal characters are replaced by underscores.

       default_privs
              Default rights for delivery to external file or command.

       forward_expansion_filter
              What characters are allowed to appear  in  $name  expansions  of
              forward_path. Illegal characters are replaced by underscores.

HISTORY
       The  Delivered-To:  header  appears in the qmail system by Daniel Bern-
       stein.

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

SEE ALSO
       aliases(5) format of alias database
       bounce(8) non-delivery status reports
       postalias(1) create/update alias database
       syslogd(8) system logging
       qmgr(8) queue manager

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



                                                                      LOCAL(8)