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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 appropriate.
CASE FOLDING
All delivery decisions are made using the bare recipient name (i.e. the address local-
part), 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 configuration 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, ~/.for-
ward 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 (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 special meaning to the shell or file system are replaced by underscores.
The list of acceptable characters is specified with the forward_expansion_filter configu-
ration 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 dupli-
cate deliveries. The duplicate_filter_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 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 config-
uration 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_com-
mand_maps and mailbox_command configuration parameters. The command executes with the
privileges of the recipient user (exceptions: secondary groups are not enabled; 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 mas-
ter.cf file. The mailbox_transport_maps and mailbox_transport configuration parameters
specify an optional message transport that is to be used for all local recipients, regard-
less of whether they are found in the UNIX passwd database. The fallback_transport_maps
and fallback_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 Delivered-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 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 com-
mands. The default setting (alias, forward) forbids command destinations in :include:
files.
Optionally, the process working directory is changed to the path specified with com-
mand_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), $recipi-
ent (complete recipient address), $extension (recipient address extension), $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 special meaning to the shell or file system are
replaced by underscores. The list of acceptable characters is specified with the execu-
tion_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 com-
mand 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 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 @ charac-
ter).
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 vari-
ables:
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 deliv-
ery.
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 Delivered-To: header with the
final 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 original length.
In the case of maildir delivery, the local daemon prepends an optional Delivered-To:
header with the final envelope recipient 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/.forward+foo or in
~name/.forward, to the mailbox owned by the user name, or it is sent back as undeliver-
able.
In all cases the local(8) daemon prepends an optional `Delivered-To: header line with the
final recipient address.
DELIVERY RIGHTS
Deliveries to external files and external commands are made with the rights of the receiv-
ing user on whose behalf the delivery 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). 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 impersonate the recipient and deliver to recipient-speci-
fied 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 lim-
ited 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 includ-
ing 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 address to the expansion of the "owner-aliasname"
alias.
owner_request_special (yes)
Give special treatment to owner-listname and listname-request address localparts:
don't split such addresses 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.
DELIVERY METHOD CONTROLS
The precedence of local(8) delivery methods from high to low is: aliases, .forward files,
mailbox_transport_maps, mailbox_transport, mailbox_command_maps, mailbox_command,
home_mailbox, mail_spool_directory, fallback_transport_maps, fallback_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-spec-
ified 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 recipients, 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 recipi-
ents 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 expansion, or for showq(8) queue displays.
local_destination_concurrency_limit (2)
The maximal number of parallel deliveries via the local mail delivery transport to
the same recipient (when "local_destination_recipient_limit = 1") or the maximal
number of parallel deliveries to the same local domain (when "local_destina-
tion_recipient_limit > 1").
local_destination_recipient_limit (1)
The maximal number of recipients per message delivery via the local mail delivery
transport.
mailbox_size_limit (51200000)
The maximal size of any local(8) individual mailbox or maildir file, or zero (no
limit).
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 $command_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 incom-
ing connection before terminating voluntarily.
max_use (100)
The maximal number of incoming connections that a Postfix daemon process will ser-
vice 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 separator between user names and address extensions (user+foo).
require_home_directory (no)
Whether or not a local(8) recipient's home directory must exist before mail deliv-
ery is attempted.
syslog_facility (mail)
The syslog facility of Postfix logging.
syslog_name (postfix)
The mail system name that is prepended to the process name in syslog records, so
that "smtpd" becomes, for example, "postfix/smtpd".
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
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
LOCAL(8postfix)
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