PIPE(8) PIPE(8)
NAME
pipe - Postfix delivery to external command
SYNOPSIS
pipe [generic Postfix daemon options] command_attributes...
DESCRIPTION
The pipe(8) daemon processes requests from the Postfix
queue manager to deliver messages to external commands.
This program expects to be run from the master(8) process
manager.
Message attributes such as sender address, recipient
address and next-hop host name can be specified as com-
mand-line macros that are expanded before the external
command is executed.
The pipe(8) daemon updates queue files and marks recipi-
ents 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.
SINGLE-RECIPIENT DELIVERY
Some external commands cannot handle more than one recipi-
ent per delivery request. Examples of such transports are
pagers, fax machines, and so on.
To prevent Postfix from sending multiple recipients per
delivery request, specify
transport_destination_recipient_limit = 1
in the Postfix main.cf file, where transport is the name
in the first column of the Postfix master.cf entry for the
pipe-based delivery transport.
COMMAND ATTRIBUTE SYNTAX
The external command attributes are given in the master.cf
file at the end of a service definition. The syntax is as
follows:
directory=pathname (optional, default: $queue_directory)
Change to the named directory before executing the
external command. Delivery is deferred in case of
failure.
This feature is available as of Postfix 2.2.
eol=string (optional, default: \n)
The output record delimiter. Typically one would
use either \r\n or \n. The usual C-style backslash
escape sequences are recognized: \a \b \f \n \r \t
\v \ddd (up to three octal digits) and \\.
flags=BDFORhqu.> (optional)
Optional message processing flags. By default, a
message is copied unchanged.
B Append a blank line at the end of each mes-
sage. This is required by some mail user
agents that recognize "From " lines only
when preceded by a blank line.
D Prepend a "Delivered-To: recipient" message
header with the envelope recipient address.
Note: for this to work, the transport_desti-
nation_recipient_limit must be 1.
This feature is available as of Postfix 2.0.
F Prepend a "From sender time_stamp" envelope
header to the message content. This is
expected by, for example, UUCP software.
O Prepend an "X-Original-To: recipient" mes-
sage header with the recipient address as
given to Postfix. Note: for this to work,
the transport_destination_recipient_limit
must be 1.
This feature is available as of Postfix 2.0.
R Prepend a Return-Path: message header with
the envelope sender address.
h Fold the command-line $recipient domain name
and $nexthop host name to lower case. This
is recommended for delivery via UUCP.
q Quote white space and other special charac-
ters in the command-line $sender and $recip-
ient address localparts (text to the left of
the right-most @ character), according to an
8-bit transparent version of RFC 822. This
is recommended for delivery via UUCP or
BSMTP.
The result is compatible with the address
parsing of command-line recipients by the
Postfix sendmail(1) mail submission command.
The q flag affects only entire addresses,
not the partial address information from the
$user, $extension or $mailbox command-line
macros.
u Fold the command-line $recipient address
localpart (text to the left of the right-
most @ character) to lower case. This is
recommended for delivery via UUCP.
. Prepend "." to lines starting with ".". This
is needed by, for example, BSMTP software.
> Prepend ">" to lines starting with "From ".
This is expected by, for example, UUCP soft-
ware.
size=size_limit (optional)
Messages greater in size than this limit (in bytes)
will be bounced back to the sender.
user=username (required)
user=username:groupname
The external command is executed with the rights of
the specified username. The software refuses to
execute commands with root privileges, or with the
privileges of the mail system owner. If groupname
is specified, the corresponding group ID is used
instead of the group ID of username.
argv=command... (required)
The command to be executed. This must be specified
as the last command attribute. The command is exe-
cuted directly, i.e. without interpretation of
shell meta characters by a shell command inter-
preter.
In the command argument vector, the following
macros are recognized and replaced with correspond-
ing information from the Postfix queue manager
delivery request.
In addition to the form ${name}, the forms $name
and $(name) are also recognized. Specify $$ where
a single $ is wanted.
${client_address}
This macro expands to the remote client net-
work address.
This is available in Postfix 2.2 and later.
${client_helo}
This macro expands to the remote client HELO
command parameter.
This is available in Postfix 2.2 and later.
${client_hostname}
This macro expands to the remote client
hostname.
This is available in Postfix 2.2 and later.
${client_protocol}
This macro expands to the remote client pro-
tocol.
This is available in Postfix 2.2 and later.
${extension}
This macro expands to the extension part of
a recipient address. For example, with an
address user+foo@domain the extension is
foo.
A command-line argument that contains
${extension} expands into as many command-
line arguments as there are recipients.
This information is modified by the u flag
for case folding.
${mailbox}
This macro expands to the complete local
part of a recipient address. For example,
with an address user+foo@domain the mailbox
is user+foo.
A command-line argument that contains
${mailbox} expands into as many command-line
arguments as there are recipients.
This information is modified by the u flag
for case folding.
${nexthop}
This macro expands to the next-hop hostname.
This information is modified by the h flag
for case folding.
${recipient}
This macro expands to the complete recipient
address.
A command-line argument that contains
${recipient} expands into as many command-
line arguments as there are recipients.
This information is modified by the hqu
flags for quoting and case folding.
${sasl_method}
This macro expands to the SASL authentica-
tion mechanism used during the reception of
the message. An empty string is passed if
the message has been received without SASL
authentication.
This is available in Postfix 2.2 and later.
${sasl_sender}
This macro expands to the SASL sender name
(i.e. the original submitter as per RFC
2554) used during the reception of the mes-
sage.
This is available in Postfix 2.2 and later.
${sasl_username}
This macro expands to the SASL user name
used during the reception of the message. An
empty string is passed if the message has
been received without SASL authentication.
This is available in Postfix 2.2 and later.
${sender}
This macro expands to the envelope sender
address.
This information is modified by the q flag
for quoting.
${size}
This macro expands to Postfix's idea of the
message size, which is an approximation of
the size of the message as delivered.
${user}
This macro expands to the username part of a
recipient address. For example, with an
address user+foo@domain the username part is
user.
A command-line argument that contains
${user} expands into as many command-line
arguments as there are recipients.
This information is modified by the u flag
for case folding.
DIAGNOSTICS
Command exit status codes are expected to follow the con-
ventions defined in <sysexits.h>.
Problems and transactions are logged to syslogd(8). Cor-
rupted message files are marked so that the queue manager
can move them to the corrupt queue for further inspection.
SECURITY
This program needs a dual personality 1) to access the
private Postfix queue and IPC mechanisms, and 2) to exe-
cute external commands as the specified user. It is there-
fore security sensitive.
CONFIGURATION PARAMETERS
Changes to main.cf are picked up automatically as pipe(8)
processes run for only a limited amount of time. Use the
command "postfix reload" to speed up a change.
The text below provides only a parameter summary. See
postconf(5) for more details including examples.
RESOURCE AND RATE CONTROLS
In the text below, transport is the first field in a mas-
ter.cf entry.
transport_destination_concurrency_limit ($default_destina-
tion_concurrency_limit)
Limit the number of parallel deliveries to the same
destination, for delivery via the named transport.
The limit is enforced by the Postfix queue manager.
transport_destination_recipient_limit ($default_destina-
tion_recipient_limit)
Limit the number of recipients per message deliv-
ery, for delivery via the named transport. The
limit is enforced by the Postfix queue manager.
transport_time_limit ($command_time_limit)
Limit the time for delivery to external command,
for delivery via the named transport. The limit is
enforced by the pipe delivery agent.
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.
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.
mail_owner (postfix)
The UNIX system account that owns the Postfix queue
and most Postfix daemon processes.
max_idle (100s)
The maximum amount of time that an idle Postfix
daemon process waits for the next service request
before exiting.
max_use (100)
The maximal number of connection requests before a
Postfix daemon process terminates.
process_id (read-only)
The process ID of a Postfix command or daemon pro-
cess.
process_name (read-only)
The process name of a Postfix command or daemon
process.
queue_directory (see 'postconf -d' output)
The location of the Postfix top-level queue direc-
tory.
recipient_delimiter (empty)
The separator between user names and address exten-
sions (user+foo).
syslog_facility (mail)
The syslog facility of Postfix logging.
syslog_name (postfix)
The mail system name that is prepended to the pro-
cess name in syslog records, so that "smtpd"
becomes, for example, "postfix/smtpd".
SEE ALSO
qmgr(8), queue manager
bounce(8), delivery status reports
postconf(5), configuration parameters
master(5), generic daemon options
master(8), process manager
syslogd(8), system logging
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
PIPE(8)