LOCAL(8) LOCAL(8)
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 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 destina-tions destinations
tions 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, ~/.forward like
files must be readable by the recipient, and their parent directory needs to have "execute" permis-sion permission
sion for the recipient.
The forward_path parameter is subject to interpolation of $user (recipient username), $home (recipi-ent (recipient
ent home directory), $shell (recipient shell), $recipient (complete recipient address), $extension
(recipient address extension), $domain (recipient domain), $local (entire recipient address local-part) localpart)
part) 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 for-ward_expansion_filter forward_expansion_filter
ward_expansion_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 deliv-eries. deliveries.
eries. 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 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 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 master.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, regardless 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 data-base. database.
base.
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 commands. The
default setting (alias, forward) forbids command destinations in :include: files.
Optionally, the process working directory is changed to the path specified with command_execu-tion_directory command_execution_directory
tion_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 user-name), username),
name), $home (recipient home directory), $shell (recipient shell), $recipient (complete recipient
address), $extension (recipient address extension), $domain (recipient domain), $local (entire recip-ient recipient
ient 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 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 spec-ified specified
ified 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 @ character).
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 Post-fix Postfix
fix 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: DeliveredTo:
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 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 undeliverable.
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 receiving 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-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) deliv-ery delivery
ery 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 exam-ples. examples.
ples.
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_deliv-ered_header) prepend_delivered_header)
ered_header) only once, at the start of a delivery attempt; do not update the Delivered-To:
address while expanding aliases or .forward files.
DELIVERY METHOD CONTROLS
The precedence of local(8) delivery methods from high to low is: aliases, .forward files, mail-box_transport_maps, mailbox_transport_maps,
box_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-specified deliv-ery delivery
ery 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 deliv-ery. delivery.
ery.
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 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_destination_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 $mail-box_command. $mailbox_command.
box_command.
default_privs (nobody)
The default rights used by the local(8) delivery agent for delivery to external file or com-mand. command.
mand.
forward_expansion_filter (see 'postconf -d' output)
Restrict the characters that the local(8) delivery agent allows in $name expansions of $for-ward_path. $forward_path.
ward_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 $com-mand_execution_directory. $command_execution_directory.
mand_execution_directory.
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 connec-tion connection
tion 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: DeliveredTo:
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 delivery 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(8)
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