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.

       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=BFR.> (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.

              .      Prepend . to lines starting with  ".".  This



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PIPE(8)                                                   PIPE(8)


                     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.

              ${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.




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PIPE(8)                                                   PIPE(8)


                     A   command-line   argument   that  contains
                     ${mailbox} expands into as many command-line
                     arguments as there are recipients.

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

              ${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.

              ${sender}
                     This  macro  expands  to the envelope sender
                     address.

              ${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.

       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



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PIPE(8)                                                   PIPE(8)


       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




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