Manual browser: pipe(8)
|PIPE(8)||System Manager's Manual||PIPE(8)|
NAMEpipe - Postfix delivery to external command
pipe [generic Postfix daemon options] command_attributes...
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.
Some destinations cannot handle more than one recipient per delivery request. Examples are pagers or fax machines. In addition, multi-recipient delivery is undesirable when prepending a Delivered-to: or X-Original-To: message header.
transport_destination_recipient_limit = 1
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:
- chroot=pathname (optional)
Change the process root directory and working directory to the named directory. This happens before switching to the privileges specified with the user attribute, and before executing the optional directory=pathname directive. Delivery is deferred in case of failure.
- directory=pathname (optional)
Change to the named directory before executing the external command. The directory must be accessible for the user specified with the user attribute (see below). The default working directory is $queue_directory. Delivery is deferred in case of failure.
- 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=BDFORXhqu.> (optional)
- Optional message processing flags. By default, a message is copied unchanged.
- Append a blank line at the end of each message. This is required by some mail user agents that recognize " From " lines only when preceded by a blank line.
Prepend a "Delivered-To: recipient" message header with the envelope recipient address. Note: for this to work, the transport_destination_recipient_limit must be 1 (see SINGLE-RECIPIENT DELIVERY above for details).
- Prepend a "From sender time_stamp" envelope header to the message content. This is expected by, for example, UUCP software.
Prepend an "X-Original-To: recipient" message header with the recipient address as given to Postfix. Note: for this to work, the transport_destination_recipient_limit must be 1 (see SINGLE-RECIPIENT DELIVERY above for details).
- Prepend a Return-Path: message header with the envelope sender address.
Indicate that the external command performs final delivery. This flag affects the status reported in "success" DSN (delivery status notification) messages, and changes it from "relayed" into "delivered".
- Fold the command-line $original_recipient and $recipient address domain part (text to the right of the right-most @ character) to lower case; fold the entire command-line $domain and $nexthop host or domain information to lower case. This is recommended for delivery via UUCP.
Quote white space and other special characters in the command-line $sender, $original_recipient and $recipient 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.
- Fold the command-line $original_recipient and $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 software.
- null_sender=replacement (default: MAILER-DAEMON)
Replace the null sender address (typically used for delivery status notifications) with the specified text when expanding the $sender command-line macro, and when generating a From_ or Return-Path: message header.
Wrong: command -f$sender -- $recipient
the command will mis-parse the -f option value when the sender address is a null string. For correct parsing, specify $sender as an argument by itself:
Right: command -f $sender -- $recipient
- This feature is available as of Postfix 2.3.
- size=size_limit (optional)
- Don't deliver messages that exceed this size limit (in bytes); return them to the sender instead.
- user=username (required)
- Execute the external command with the user ID and group ID 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 executed directly, i.e. without interpretation of shell meta characters by a shell command interpreter.
This macro expands to the remote client network address.
This macro expands to the remote client HELO command parameter.
This macro expands to the remote client hostname.
This macro expands to the remote client TCP port number.
This macro expands to the remote client protocol.
This macro expands to the domain portion of the recipient address. For example, with an address user+foo@domain the domain is domain.
This macro expands to the extension part of a recipient address. For example, with an address user+foo@domain the extension is foo.
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.
This macro expands to the next-hop hostname.
This macro expands to the complete recipient address before any address rewriting or aliasing.
This macro expands to the queue id.
This macro expands to the complete recipient address.
This macro expands to the name of the SASL authentication mechanism in the AUTH command when the Postfix SMTP server received the message.
This macro expands to the SASL sender name (i.e. the original submitter as per RFC 4954) in the MAIL FROM command when the Postfix SMTP server received the message.
This macro expands to the SASL user name in the AUTH command when the Postfix SMTP server received the message.
This macro expands to the envelope sender address. By default, the null sender address expands to MAILER-DAEMON; this can be changed with the null_sender attribute, as described above.
- This macro expands to Postfix's idea of the message size, which is an approximation of the size of the message as delivered.
This macro expands to the username part of a recipient address. For example, with an address user+foo@domain the username part is user.
RFC 3463 (Enhanced status codes)
Command exit status codes are expected to follow the conventions defined in < sysexits.h>. Exit status 0 means normal successful completion.
This program needs a dual personality 1) to access the private Postfix queue and IPC mechanisms, and 2) to execute external commands as the specified user. It is therefore security sensitive.
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.
RESOURCE AND RATE CONTROLS
In the text below, transport is the first field in a master.cf entry.
- transport_destination_concurrency_limit ($default_destination_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 ($default_destination_recipient_limit)
- Limit the number of recipients per message delivery, for delivery via the named transport. The limit is enforced by the Postfix queue manager.
- transport_time_limit ($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.
- 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.
- 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 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.
- 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.
- 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).
- syslog_facility (mail)
- The syslog facility of Postfix logging.
- syslog_name (see 'postconf -d' output)
- The mail system name that is prepended to the process name in syslog records, so that "smtpd" becomes, for example, "postfix/smtpd".
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
The Secure Mailer license must be distributed with this software.
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA