PIPE(8) PIPE(8)
NAME
pipe - Postfix delivery to external command
SYNOPSIS
pipe [generic Postfix daemon options] command_attributes...
DESCRIPTION
The pipe 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 man-
ager.
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 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.
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:
flags=BFRhqu.> (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.
F Prepend a "From sender time_stamp" envelope
header to the message content. This is
expected by, for example, UUCP software.
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 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.
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.
eol=string (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 \octal and \\.
size=size_limit (optional)
Messages greater in size than this limit (in bytes)
will be bounced back to the sender.
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:
${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.
${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.
In addition to the form ${name}, the forms $name and
$(name) are also recognized. Specify $$ where a single $
is wanted.
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
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
export_environment
List of names of environment parameters that can be
exported to non-Postfix processes.
mail_owner
The process privileges used while not running an
external command.
Resource controls
In the text below, transport is the first field in a mas-
ter.cf entry.
transport_destination_concurrency_limit
Limit the number of parallel deliveries to the same
destination, for delivery via the named transport.
The default limit is taken from the default_desti-
nation_concurrency_limit parameter. The limit is
enforced by the Postfix queue manager.
transport_destination_recipient_limit
Limit the number of recipients per message deliv-
ery, for delivery via the named transport. The
default limit is taken from the default_destina-
tion_recipient_limit parameter. The limit is
enforced by the Postfix queue manager.
transport_time_limit
Limit the time for delivery to external command,
for delivery via the named transport. The default
limit is taken from the command_time_limit parame-
ter. The limit is enforced by the Postfix queue
manager.
SEE ALSO
bounce(8) non-delivery status reports
master(8) process manager
qmgr(8) queue 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
1