LOCAL(8)                                                 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 mas-
       ter(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 send-
       mail-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 sepa-
       rated list of  ~/.forward  like  files  through  the  for-
       ward_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
       interpolation of $user (recipient username), $home (recip-
       ient home directory), $shell (recipient shell), $recipient
       (complete  recipient   address),   $extension   (recipient
       address  extension),  $domain  (recipient  domain),  local
       (entire recipient address localpart) and $recipient_delim-
       iter.  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_expan-
       sion_filter configuration parameter.
       An alias or ~/.forward file may list  any  combination  of
       external   commands,  destination  file  names,  :include:
       directives, or mail addresses.  See aliases(5) for a  pre-
       cise  description. Each line in a user's .forward 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 ~/.forward file
       means do not forward mail.
       In order to prevent the mail system from using  up  unrea-
       sonable   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 dupli-
       cate_filter_limit  configuration parameter limits the num-
       ber of remembered recipients.
MAIL FORWARDING
       For the sake of reliability, forwarded mail is  re-submit-
       ted  as  a new message, so that each recipient has a sepa-
       rate 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_direc-
       tory  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 parame-
       ter. 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  mail-
       box_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 database.
       In the case of UNIX-style mailbox delivery, the local dae-
       mon 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 set-
       ting (alias,  forward)  forbids  command  destinations  in
       :include: files.
       The  command  is  executed directly where possible. Assis-
       tance 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-deliv-
       ery status reports.  A command is forcibly  terminated  if
       it  does  not  complete within command_time_limit seconds.
       Command exit status codes are expected to follow the  con-
       ventions defined in <sysexits.h>.
       A  limited amount of message context is exported via envi-
       ronment variables. Characters that may have special  mean-
       ing to the shell are replaced by underscores.  The list of
       acceptable characters is specified with the command_expan-
       sion_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" enve-
       lope  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 recipi-
       ent 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 destinations in :include: files.
       In the case of UNIX-style mailbox delivery, the local dae-
       mon 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  > 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 orig-
       inal length.
       In the case of maildir delivery, the local daemon prepends
       an optional Delivered-To: header with the envelope recipi-
       ent  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  destinations  listed in ~name/.for-
       ward+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 `Deliv-
       ered-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).   Cor-
       rupted  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  postmaster  is notified of bounces and of other trou-
       ble.
BUGS
       For security  reasons,  the  message  delivery  status  of
       external  commands  or  of  external files is never check-
       pointed to file. As a result, the program may occasionally
       deliver more than once to a command or external file. Bet-
       ter 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 Delivered-To: message header.
CONFIGURATION PARAMETERS
       The following main.cf parameters are  especially  relevant
       to  this  program. 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 network service.
       expand_owner_alias
              When delivering to an alias that has an owner- com-
              panion  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 sub-
              ject 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 con-
              tains no shell built-in commands  or  meta  charac-
              ters.
       owner_request_special
              Give special treatment to owner-xxx and xxx-request
              addresses.
       prepend_delivered_header
              Prepend  an  optional  Delivered-To:  header   upon
              external  forwarding,  delivery to command or file.
              Specify zero or more of:  command,  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 acces-
              sible  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 over-
              rides luser_relay.
              Note: you must update the local_recipient_maps set-
              ting  in  the  main.cf  file, otherwise the Postfix
              SMTP server will reject mail for non-UNIX  accounts
              with "User unknown in local recipient table".
       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  expan-
              sion.
              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  end-
              ing in / for maildir-style delivery.
       mailbox_command
              External  command  to use for mailbox delivery. The
              command  executes  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  over-
              rides  all other configuration parameters that con-
              trol 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 exclu-
              sive lock on a mailbox or external file.
       deliver_lock_delay
              Time in  seconds  between  successive  attempts  to
              acquire an exclusive 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 command.
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_concurrency_limit parameter.
       local_destination_recipient_limit
              Limit the number of recipients per  message  deliv-
              ery.    The   default   limit  is  taken  from  the
              default_destination_recipient_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.   Specify 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 Bernstein.
       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)