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 adminstrator 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.

       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.



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LOCAL(8)                                                 LOCAL(8)


       In order to stop mail forwarding loops early, the software
       adds a 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  per-user mailbox is either a file in the default UNIX
       mailbox directory (/var/mail/user or /var/spool/mail/user)
       or  it  is a file in the user's home directory with a name
       specified via the  home_mailbox  configuration  parameter.
       Mailbox  delivery  can be delegated to an external command
       specified with the mailbox_command  configuration  parame-
       ter.

       The local daemon prepends a "From sender time_stamp" enve-
       lope header to  each  message,  prepends  a  Delivered-To:
       header  with  the envelope recipient 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.

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>.

       When mail is delivered on behalf of a user, the HOME, LOG-
       NAME, and SHELL environment variables are set accordingly.
       The PATH environment variable is always reset to a system-
       dependent default path, and the TZ (time zone) environment
       variable is always passed on without change.

       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 a Delivered-To:
       header with the recipient envelope address, and appends an
       empty line.




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LOCAL(8)                                                 LOCAL(8)


EXTERNAL FILE DELIVERY
       The  allow_mail_to_files configuration parameter restricts
       delivery to external files. The  default  setting  (alias,
       forward) forbids file destinations in :include: files.

       The local daemon prepends a "From sender time_stamp" enve-
       lope header to  each  message,  prepends  a  Delivered-To:
       header  with  the recipient envelope address, prepends a >
       character to lines beginning with "From ", and appends  an
       empty line.  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 reg-
       ular file to its original length.

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  a  `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).  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.



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LOCAL(8)                                                 LOCAL(8)


       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 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.

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

       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.

       mailbox_command
              External command to use for mailbox delivery.

       recipient_delimiter
              Separator between username and address extension.

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.

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.



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LOCAL(8)                                                 LOCAL(8)


       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.

Security controls
       allow_mail_to_commands
              Restrict the usage of  mail  delivery  to  external
              command.

       allow_mail_to_files
              Restrict  the  usage  of  mail delivery to external
              file.

       default_privs
              Default rights for delivery  to  external  file  or
              command.

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







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