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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 command-line macros that are expanded
       before the external command is executed.

       The  pipe(8)  daemon  updates  queue files and marks recipients as fin‐
       ished, 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 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.

       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:

       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.

	      This feature is available as of Postfix 2.3.

       directory=pathname (optional)
	      Change to the named directory before executing the external com‐
	      mand.  The directory must be accessible for the  user  specified
	      with the user attribute (see below).  The default working direc‐
	      tory is $queue_directory.	 Delivery is deferred in case of fail‐
	      ure.

	      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	recog‐
	      nized:  \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.

	      B	     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.

	      D	     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).

		     The D flag also enforces loop detection (Postfix 2.5  and
		     later):  if  a  message  already contains a Delivered-To:
		     header with the same recipient address, then the  message
		     is	 returned  as undeliverable. The address comparison is
		     case insensitive.

		     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" 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).

		     This feature is available as of Postfix 2.0.

	      R	     Prepend  a	 Return-Path: message header with the envelope
		     sender address.

	      X	     Indicate that the external command performs final	deliv‐
		     ery.   This flag affects the status reported in "success"
		     DSN (delivery status notification) messages, and  changes
		     it from "relayed" into "delivered".

		     This feature is available as of Postfix 2.5.

	      h	     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.

	      q	     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.

		     The result is compatible with the address parsing of com‐
		     mand-line recipients by the Postfix sendmail(1) mail sub‐
		     mission command.

		     The q flag affects only entire addresses, not the partial
		     address  information from the $user, $extension or $mail‐
		     box command-line macros.

	      u	     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 deliv‐
		     ery 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.

	      If the null sender replacement text is a non-empty  string  then
	      it is affected by the q flag for address quoting in command-line
	      arguments.

	      The null sender replacement text may be empty; this form is rec‐
	      ommended	for  content filters that feed mail back into Postfix.
	      The empty sender address is not  affected	 by  the  q  flag  for
	      address quoting in command-line arguments.

	      Caution:	a  null	 sender	 address is easily mis-parsed by naive
	      software. For example, when the pipe(8) daemon executes  a  com‐
	      mand such as:

		  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)

       user=username:groupname
	      Execute the external command with the user ID and	 group	ID  of
	      the  specified  username.	  The software refuses to execute com‐
	      mands 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. with‐
	      out interpretation of shell meta characters by a	shell  command
	      interpreter.

	      In  the command argument vector, the following macros are recog‐
	      nized and replaced with corresponding information from the Post‐
	      fix 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 network address.

		     This feature is available as of Postfix 2.2.

	      ${client_helo}
		     This macro expands to  the	 remote	 client	 HELO  command
		     parameter.

		     This feature is available as of Postfix 2.2.

	      ${client_hostname}
		     This macro expands to the remote client hostname.

		     This feature is available as of Postfix 2.2.

	      ${client_port}
		     This macro expands to the remote client TCP port number.

		     This feature is available as of Postfix 2.5.

	      ${client_protocol}
		     This macro expands to the remote client protocol.

		     This feature is available as of Postfix 2.2.

	      ${domain}
		     This macro expands to the domain portion of the recipient
		     address.  For example, with  an  address  user+foo@domain
		     the domain is domain.

		     This information is modified by the h flag for case fold‐
		     ing.

		     This feature is available as of Postfix 2.5.

	      ${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 fold‐
		     ing.

	      ${mailbox}
		     This macro expands to the complete local part of a recip‐
		     ient   address.	For   example,	 with	 an    address
		     user+foo@domain the mailbox is user+foo.

		     A	command-line argument that contains ${mailbox} expands
		     to as many command-line arguments as  there  are  recipi‐
		     ents.

		     This information is modified by the u flag for case fold‐
		     ing.

	      ${nexthop}
		     This macro expands to the next-hop hostname.

		     This information is modified by the h flag for case fold‐
		     ing.

	      ${original_recipient}
		     This  macro  expands  to  the  complete recipient address
		     before any address rewriting or aliasing.

		     A command-line argument that contains  ${original_recipi‐
		     ent}  expands  to as many command-line arguments as there
		     are recipients.

		     This information is modified by the hqu flags for quoting
		     and case folding.

		     This feature is available as of Postfix 2.5.

	      ${recipient}
		     This macro expands to the complete recipient address.

		     A	 command-line	argument  that	contains  ${recipient}
		     expands to 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 name of the SASL authentication
		     mechanism	in  the	 AUTH  command	when  the Postfix SMTP
		     server received the message.

		     This feature is available as of Postfix 2.2.

	      ${sasl_sender}
		     This macro expands to the	SASL  sender  name  (i.e.  the
		     original submitter as per RFC 4954) in the MAIL FROM com‐
		     mand when the Postfix SMTP server received the message.

		     This feature is available as of Postfix 2.2.

	      ${sasl_username}
		     This macro expands to the SASL user name in the AUTH com‐
		     mand when the Postfix SMTP server received the message.

		     This feature is available as of Postfix 2.2.

	      ${sender}
		     This  macro  expands  to  the envelope sender address. By
		     default, the null sender address expands  to  MAILER-DAE‐
		     MON;  this can be changed with the null_sender attribute,
		     as described above.

		     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 recipi‐
		     ents.

		     This information is modified by the u flag for case fold‐
		     ing.

STANDARDS
       RFC 3463 (Enhanced status codes)

DIAGNOSTICS
       Command	exit  status  codes  are  expected  to	follow the conventions
       defined in <sysexits.h>.	 Exit status 0 means normal successful comple‐
       tion.

       In the case of a non-zero exit status, a limited amount of command out‐
       put is reported in an delivery status notification.   When  the	output
       begins  with  a	4.X.X  or  5.X.X enhanced status code, the status code
       takes precedence over the non-zero exit status (Postfix version 2.3 and
       later).

       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 for further inspection.

SECURITY
       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.

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 master.cf entry.

       transport_destination_concurrency_limit	 ($default_destination_concur‐
       rency_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_recipi‐
       ent_limit)
	      Limit the number of recipients per message delivery, for	deliv‐
	      ery via the named transport.  The limit is enforced by the Post‐
	      fix 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.

	      Postfix 2.4 and later support a suffix that specifies  the  time
	      unit:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
	      The default time unit is seconds.

MISCELLANEOUS CONTROLS
       config_directory (see 'postconf -d' output)
	      The default location of the Postfix main.cf and  master.cf  con‐
	      figuration 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  log‐
	      ging 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  separator  between  user  names  and	  address   extensions
	      (user+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,	"post‐
	      fix/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)
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