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<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<html> <head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel='stylesheet' type='text/css' href='postfix-doc.css'>
<title> Postfix manual - pipe(8) </title>
</head> <body> <pre>
PIPE(8)                                                                PIPE(8)

<b>NAME</b>
       pipe - Postfix delivery to external command

<b>SYNOPSIS</b>
       <b>pipe</b> [generic Postfix daemon options] command_attributes...

<b>DESCRIPTION</b>
       The <a href="pipe.8.html"><b>pipe</b>(8)</a> daemon processes requests from the Postfix queue manager to
       deliver messages to external commands.  This program expects to be  run
       from the <a href="master.8.html"><b>master</b>(8)</a> 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  <a href="pipe.8.html"><b>pipe</b>(8)</a>  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
       <a href="bounce.8.html"><b>bounce</b>(8)</a>, <a href="defer.8.html"><b>defer</b>(8)</a> or <a href="trace.8.html"><b>trace</b>(8)</a> daemon as appropriate.

<b>SINGLE-RECIPIENT DELIVERY</b>
       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 <b>Delivered-to:</b>
       or <b>X-Original-To:</b> message header.

       To  prevent  Postfix  from  sending  multiple  recipients  per delivery
       request, specify

           <b><a href="postconf.5.html#transport_destination_recipient_limit"><i>transport</i>_destination_recipient_limit</a> = 1</b>

       in the Postfix <a href="postconf.5.html"><b>main.cf</b></a> file, where <i>transport</i> is the name in  the  first
       column  of  the  Postfix  <a href="master.5.html"><b>master.cf</b></a>  entry  for the pipe-based delivery
       transport.

<b>COMMAND ATTRIBUTE SYNTAX</b>
       The external command attributes are given in the <a href="master.5.html"><b>master.cf</b></a> file at  the
       end of a service definition.  The syntax is as follows:

       <b>chroot=</b><i>pathname</i> (optional)
              Change  the  process root directory and working directory to the
              named directory. This happens before switching to the privileges
              specified  with  the  <b>user</b>  attribute,  and before executing the
              optional <b>directory=</b><i>pathname</i> directive. Delivery is  deferred  in
              case of failure.

              This feature is available as of Postfix 2.3.

       <b>directory=</b><i>pathname</i> (optional)
              Change to the named directory before executing the external com-
              mand.  The directory must be accessible for the  user  specified
              with the <b>user</b> attribute (see below).  The default working direc-
              tory is <b>$<a href="postconf.5.html#queue_directory">queue_directory</a></b>.  Delivery is deferred in case of fail-
              ure.

              This feature is available as of Postfix 2.2.

       <b>eol=</b><i>string</i> (optional, default: <b>\n</b>)
              The output record delimiter. Typically one would use either <b>\r\n</b>
              or <b>\n</b>. The usual C-style backslash escape sequences  are  recog-
              nized:  <b>\a \b \f \n \r \t \v \</b><i>ddd</i> (up to three octal digits) and
              <b>\\</b>.

       <b>flags=BDFORXhqu.</b>&gt; (optional)
              Optional message processing flags.  By  default,  a  message  is
              copied unchanged.

              <b>B</b>      Append  a  blank line at the end of each message. This is
                     required by some mail user agents that recognize "<b>From</b>  "
                     lines only when preceded by a blank line.

              <b>D</b>      Prepend  a  "<b>Delivered-To:</b> <i>recipient</i>" message header with
                     the envelope recipient address. Note: for this  to  work,
                     the  <b><a href="postconf.5.html#transport_destination_recipient_limit"><i>transport</i>_destination_recipient_limit</a></b> must be 1 (see
                     SINGLE-RECIPIENT DELIVERY above for details).

                     The <b>D</b> flag also enforces loop detection (Postfix 2.5  and
                     later):  if  a  message  already contains a <b>Delivered-To:</b>
                     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.

              <b>F</b>      Prepend a "<b>From</b> <i>sender time</i><b>_</b><i>stamp</i>" envelope header to the
                     message  content.  This is expected by, for example, <b>UUCP</b>
                     software.

              <b>O</b>      Prepend an "<b>X-Original-To:</b> <i>recipient</i>" message header with
                     the recipient address as given to Postfix. Note: for this
                     to work, the  <b><a href="postconf.5.html#transport_destination_recipient_limit"><i>transport</i>_destination_recipient_limit</a></b>  must
                     be 1 (see SINGLE-RECIPIENT DELIVERY above for details).

                     This feature is available as of Postfix 2.0.

              <b>R</b>      Prepend  a  <b>Return-Path:</b> message header with the envelope
                     sender address.

              <b>X</b>      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.

              <b>h</b>      Fold  the command-line <b>$original_recipient</b> and <b>$recipient</b>
                     address domain part (text to the right of the  right-most
                     <b>@</b>  character) to lower case; fold the entire command-line
                     <b>$domain</b> and <b>$nexthop</b> host or domain information to  lower
                     case.  This is recommended for delivery via <b>UUCP</b>.

              <b>q</b>      Quote  white  space  and  other special characters in the
                     command-line <b>$sender</b>, <b>$original_recipient</b> and  <b>$recipient</b>
                     address  localparts (text to the left of the right-most <b>@</b>
                     character), according to an 8-bit transparent version  of
                     <a href="https://tools.ietf.org/html/rfc822">RFC  822</a>.   This  is recommended for delivery via <b>UUCP</b> or
                     <b>BSMTP</b>.

                     The result is compatible with the address parsing of com-
                     mand-line recipients by the Postfix <a href="sendmail.1.html"><b>sendmail</b>(1)</a> mail sub-
                     mission command.

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

              <b>u</b>      Fold the command-line <b>$original_recipient</b> and  <b>$recipient</b>
                     address  localpart  (text to the left of the right-most <b>@</b>
                     character) to lower case.  This is recommended for deliv-
                     ery via <b>UUCP</b>.

              <b>.</b>      Prepend  "<b>.</b>"  to  lines starting with "<b>.</b>". This is needed
                     by, for example, <b>BSMTP</b> software.

              &gt;      Prepend "&gt;" to lines  starting  with  "<b>From</b>  ".  This  is
                     expected by, for example, <b>UUCP</b> software.

       <b>null_sender</b>=<i>replacement</i> (default: MAILER-DAEMON)
              Replace  the  null  sender  address (typically used for delivery
              status notifications) with the specified text when expanding the
              <b>$sender</b>  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 <b>q</b> 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  <b>q</b>  flag  for
              address quoting in command-line arguments.

              Caution:  a  null  sender  address is easily mis-parsed by naive
              software. For example, when the <a href="pipe.8.html"><b>pipe</b>(8)</a> daemon executes  a  com-
              mand such as:

                  <i>Wrong</i>: 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  <b>$sender</b>
              as an argument by itself:

                  <i>Right</i>: command -f $sender -- $recipient
              NOTE: DO NOT put quotes around the command, $sender, or $recipi-
              ent.

              This feature is available as of Postfix 2.3.

       <b>size</b>=<i>size</i><b>_</b><i>limit</i> (optional)
              Don't deliver messages that exceed this size limit  (in  bytes);
              return them to the sender instead.

       <b>user</b>=<i>username</i> (required)

       <b>user</b>=<i>username</i>:<i>groupname</i>
              Execute  the  external  command with the user ID and group ID of
              the specified <i>username</i>.  The software refuses  to  execute  com-
              mands  with  root privileges, or with the privileges of the mail
              system owner. If <i>groupname</i> is specified, the corresponding group
              ID is used instead of the group ID of <i>username</i>.

       <b>argv</b>=<i>command</i>... (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.

              Specify "{" and "}" around command arguments that contain white-
              space  (Postfix 3.0 and later). Whitespace after the opening "{"
              and before the closing "}" is ignored.

              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 ${<i>name</i>}, the forms $<i>name</i> and the  depre-
              cated form $(<i>name</i>) are also recognized.  Specify <b>$$</b> where a sin-
              gle <b>$</b> is wanted.

              <b>${client_address}</b>
                     This macro expands to the remote client network  address.

                     This feature is available as of Postfix 2.2.

              <b>${client_helo}</b>
                     This  macro  expands  to  the  remote client HELO command
                     parameter.

                     This feature is available as of Postfix 2.2.

              <b>${client_hostname}</b>
                     This macro expands to the remote client hostname.

                     This feature is available as of Postfix 2.2.

              <b>${client_port}</b>
                     This macro expands to the remote client TCP port  number.

                     This feature is available as of Postfix 2.5.

              <b>${client_protocol}</b>
                     This macro expands to the remote client protocol.

                     This feature is available as of Postfix 2.2.

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

                     This information is modified by the <b>h</b> flag for case fold-
                     ing.

                     This feature is available as of Postfix 2.5.

              <b>${extension}</b>
                     This macro expands to the extension part of  a  recipient
                     address.   For  example,  with an address <i>user+foo@domain</i>
                     the extension is <i>foo</i>.

                     A  command-line  argument  that   contains   <b>${extension}</b>
                     expands  into as many command-line arguments as there are
                     recipients.

                     This information is modified by the <b>u</b> flag for case fold-
                     ing.

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

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

                     This information is modified by the <b>u</b> flag for case fold-
                     ing.

              <b>${nexthop}</b>
                     This macro expands to the next-hop hostname.

                     This information is modified by the <b>h</b> flag for case fold-
                     ing.

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

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

                     This information is modified by the <b>hqu</b> flags for quoting
                     and case folding.

                     This feature is available as of Postfix 2.5.

              <b>${queue_id}</b>
                     This macro expands to the queue id.

                     This feature is available as of Postfix 2.11.

              <b>${recipient}</b>
                     This macro expands to the complete recipient address.

                     A   command-line   argument  that  contains  <b>${recipient}</b>
                     expands to as many command-line arguments  as  there  are
                     recipients.

                     This information is modified by the <b>hqu</b> flags for quoting
                     and case folding.

              <b>${sasl_method}</b>
                     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.

              <b>${sasl_sender}</b>
                     This macro expands to the  SASL  sender  name  (i.e.  the
                     original submitter as per <a href="https://tools.ietf.org/html/rfc4954">RFC 4954</a>) in the MAIL FROM com-
                     mand when the Postfix SMTP server received the message.

                     This feature is available as of Postfix 2.2.

              <b>${sasl_username}</b>
                     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.

              <b>${sender}</b>
                     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 <b>null_sender</b> attribute,
                     as described above.

                     This information is modified by the <b>q</b> flag for quoting.

              <b>${size}</b>
                     This macro expands to Postfix's idea of the message size,
                     which  is  an approximation of the size of the message as
                     delivered.

              <b>${user}</b>
                     This macro expands to the username part  of  a  recipient
                     address.   For  example,  with an address <i>user+foo@domain</i>
                     the username part is <i>user</i>.

                     A command-line argument  that  contains  <b>${user}</b>  expands
                     into  as many command-line arguments as there are recipi-
                     ents.

                     This information is modified by the <b>u</b> flag for case fold-
                     ing.

<b>STANDARDS</b>
       <a href="https://tools.ietf.org/html/rfc3463">RFC 3463</a> (Enhanced status codes)

<b>DIAGNOSTICS</b>
       Command  exit  status  codes  are  expected  to  follow the conventions
       defined in &lt;<b>sysexits.h</b>&gt;.  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 logged, and reported in a delivery  status  notification.   When
       the  output begins with a 4.X.X or 5.X.X enhanced status code, the sta-
       tus code takes precedence over the non-zero exit status  (Postfix  ver-
       sion 2.3 and later).

       After  successful  delivery (zero exit status) a limited amount of com-
       mand output is logged, and reported in "success" delivery status  noti-
       fications (Postfix 3.0 and later).  This command output is not examined
       for the presence of an enhanced status code.

       Problems and transactions are  logged  to  <b>syslogd</b>(8)  or  <a href="postlogd.8.html"><b>postlogd</b>(8)</a>.
       Corrupted  message  files are marked so that the queue manager can move
       them to the <b>corrupt</b> queue for further inspection.

<b>SECURITY</b>
       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.

<b>CONFIGURATION PARAMETERS</b>
       Changes to <a href="postconf.5.html"><b>main.cf</b></a> are picked up automatically as <a href="pipe.8.html"><b>pipe</b>(8)</a> processes run
       for  only a limited amount of time. Use the command "<b>postfix reload</b>" to
       speed up a change.

       The text below provides only a parameter summary. See  <a href="postconf.5.html"><b>postconf</b>(5)</a>  for
       more details including examples.

<b>RESOURCE AND RATE CONTROLS</b>
       In the text below, <i>transport</i> is the first field in a <a href="master.5.html"><b>master.cf</b></a> entry.

       <b><a href="postconf.5.html#transport_time_limit">transport_time_limit</a> ($<a href="postconf.5.html#command_time_limit">command_time_limit</a>)</b>
              A transport-specific override for the <a href="postconf.5.html#command_time_limit">command_time_limit</a> parame-
              ter value, where <i>transport</i> is the <a href="master.5.html">master.cf</a> name of the  message
              delivery transport.

       Implemented in the <a href="qmgr.8.html">qmgr(8)</a> daemon:

       <b><a href="postconf.5.html#transport_destination_concurrency_limit">transport_destination_concurrency_limit</a>   ($<a href="postconf.5.html#default_destination_concurrency_limit">default_destination_concur</a>-</b>
       <b><a href="postconf.5.html#default_destination_concurrency_limit">rency_limit</a>)</b>
              A  transport-specific  override for the <a href="postconf.5.html#default_destination_concurrency_limit">default_destination_con</a>-
              <a href="postconf.5.html#default_destination_concurrency_limit">currency_limit</a> parameter value, where <i>transport</i> is the <a href="master.5.html">master.cf</a>
              name of the message delivery transport.

       <b><a href="postconf.5.html#transport_destination_recipient_limit">transport_destination_recipient_limit</a>     ($<a href="postconf.5.html#default_destination_recipient_limit">default_destination_recipi</a>-</b>
       <b><a href="postconf.5.html#default_destination_recipient_limit">ent_limit</a>)</b>
              A transport-specific override for the <a href="postconf.5.html#default_destination_recipient_limit">default_destination_recip</a>-
              <a href="postconf.5.html#default_destination_recipient_limit">ient_limit</a> parameter value, where  <i>transport</i>  is  the  <a href="master.5.html">master.cf</a>
              name of the message delivery transport.

<b>MISCELLANEOUS CONTROLS</b>
       <b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
              The  default  location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
              figuration files.

       <b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b>
              How much time a Postfix daemon process  may  take  to  handle  a
              request before it is terminated by a built-in watchdog timer.

       <b><a href="postconf.5.html#delay_logging_resolution_limit">delay_logging_resolution_limit</a> (2)</b>
              The  maximal  number of digits after the decimal point when log-
              ging sub-second delay values.

       <b><a href="postconf.5.html#export_environment">export_environment</a> (see 'postconf -d' output)</b>
              The list of environment variables that a  Postfix  process  will
              export to non-Postfix processes.

       <b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b>
              The  time  limit  for  sending  or receiving information over an
              internal communication channel.

       <b><a href="postconf.5.html#mail_owner">mail_owner</a> (postfix)</b>
              The UNIX system account that owns the  Postfix  queue  and  most
              Postfix daemon processes.

       <b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b>
              The  maximum  amount of time that an idle Postfix daemon process
              waits for an incoming connection before terminating voluntarily.

       <b><a href="postconf.5.html#max_use">max_use</a> (100)</b>
              The maximal number of incoming connections that a Postfix daemon
              process will service before terminating voluntarily.

       <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b>
              The process ID of a Postfix command or daemon process.

       <b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b>
              The process name of a Postfix command or daemon process.

       <b><a href="postconf.5.html#queue_directory">queue_directory</a> (see 'postconf -d' output)</b>
              The location of the Postfix top-level queue directory.

       <b><a href="postconf.5.html#recipient_delimiter">recipient_delimiter</a> (empty)</b>
              The set of characters that can separate an email address  local-
              part, user name, or a .forward file name from its extension.

       <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b>
              The syslog facility of Postfix logging.

       <b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b>
              A  prefix  that  is  prepended  to  the  process  name in syslog
              records, so that, for example, "smtpd" becomes "prefix/smtpd".

       Available in Postfix version 3.0 and later:

       <b><a href="postconf.5.html#pipe_delivery_status_filter">pipe_delivery_status_filter</a> ($<a href="postconf.5.html#default_delivery_status_filter">default_delivery_status_filter</a>)</b>
              Optional filter for the <a href="pipe.8.html"><b>pipe</b>(8)</a> delivery  agent  to  change  the
              delivery status code or explanatory text of successful or unsuc-
              cessful deliveries.

       Available in Postfix version 3.3 and later:

       <b><a href="postconf.5.html#enable_original_recipient">enable_original_recipient</a> (yes)</b>
              Enable support for  the  original  recipient  address  after  an
              address  is  rewritten  to a different address (for example with
              aliasing or with canonical mapping).

       <b><a href="postconf.5.html#service_name">service_name</a> (read-only)</b>
              The <a href="master.5.html">master.cf</a> service name of a Postfix daemon process.

       Available in Postfix 3.5 and later:

       <b><a href="postconf.5.html#info_log_address_format">info_log_address_format</a> (external)</b>
              The email address form that will be used  in  non-debug  logging
              (info, warning, etc.).

<b>SEE ALSO</b>
       <a href="qmgr.8.html">qmgr(8)</a>, queue manager
       <a href="bounce.8.html">bounce(8)</a>, delivery status reports
       <a href="postconf.5.html">postconf(5)</a>, configuration parameters
       <a href="master.5.html">master(5)</a>, generic daemon options
       <a href="master.8.html">master(8)</a>, process manager
       <a href="postlogd.8.html">postlogd(8)</a>, Postfix logging
       syslogd(8), system logging

<b>LICENSE</b>
       The Secure Mailer license must be distributed with this software.

<b>AUTHOR(S)</b>
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

                                                                       PIPE(8)
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