    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.

           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);
           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  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 envelope recipi-
           ent  address  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.

           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 an  optional  Deliv-
           ered-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 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  optional  Delivered-To:  header
           with  the recipient envelope address, prepends a > charac-
           ter 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 recipi-
           ent  address.  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.

           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.

           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.

    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

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