LOCAL(8postfix)                                                                                                     LOCAL(8postfix)

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 finished, 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 ap‐
       propriate.

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 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 configu‐
       ration 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 recipient.  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 (recipient  username),  $home  (recipient  home  directory),
       $shell (recipient shell), $recipient (complete recipient address), $extension (recipient address extension), $domain (recip‐
       ient  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 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 precise 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 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_fil‐
       ter_limit configuration 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 re‐
       cipient 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 loca‐
       tion 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 config‐
       uration parameters. The command executes with the privileges of the recipient user (exceptions: secondary groups are not en‐
       abled; 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_trans‐
       port_maps  and  mailbox_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 fallback_transport_maps  and  fall‐
       back_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 Deliv‐
       ered-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 exclusive ac‐
       cess 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  recipi‐
       ent  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, for‐
       ward) forbids command destinations in :include: files.

       Optionally, the process working directory is changed to the path specified 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 interpolation of $user (recipient username), $home  (recipient
       home  directory),  $shell  (recipient  shell), $recipient (complete recipient address), $extension (recipient address exten‐
       sion), $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 spe‐
       cial meaning to the shell or file system are replaced by underscores.  The list of acceptable characters is  specified  with
       the execution_directory_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 command_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 variables. Characters that may have special meaning  to  the
       shell are replaced by underscores.  The list of acceptable characters is specified with the command_expansion_filter config‐
       uration 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 following 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 destinations 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  Deliv‐
       ered-To:  header  with the final recipient envelope address, prepends a > character to lines beginning with "From ", and ap‐
       pends an empty line.  The envelope sender address is available in the Return-Path: header.  When the destination is a  regu‐
       lar  file, it is locked for exclusive access while delivery is in progress. In case of problems, an attempt is made to trun‐
       cate 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  recipi‐
       ent  address, and prepends an X-Original-To: header with the recipient address as given to Postfix.  The envelope sender ad‐
       dress 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/.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 deliv‐
       ery 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) or postlogd(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 postmaster 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 imper‐
       sonate the recipient and deliver to recipient-specified files or commands. It is therefore 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 external 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 Delivered-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 ad‐
              dress 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 recipient.

       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 unsuc‐
              cessful deliveries.

DELIVERY METHOD CONTROLS
       The precedence of local(8) delivery methods from high to low is:  aliases,  .forward  files,  mailbox_transport_maps,  mail‐
       box_transport,  mailbox_command_maps,  mailbox_command,  home_mailbox,  mail_spool_directory, fallback_transport_maps, fall‐
       back_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 re‐
              cipients, 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 duplicate filter for aliases(5) or virtual(5) alias  expan‐
              sion, 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 "lo‐
              cal_destination_recipient_limit = 1") or the maximal number of parallel deliveries to the  same  local  domain  (when
              "local_destination_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 $com‐
              mand_execution_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 recipient.

MISCELLANEOUS CONTROLS
       config_directory (see 'postconf -d' output)
              The default location of the Postfix main.cf and master.cf configuration 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 logging 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 command.

       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) delivery 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  "pre‐
              fix/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
       postlogd(8), Postfix logging
       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(8postfix)