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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 daemon processes requests from the Postfix queue
       manager to deliver messages  to  external  commands.  Each
       delivery request specifies a queue file, a sender address,
       a domain or host to deliver to, and one  or  more  recipi-
       ents.   This  program expects to be run from the master(8)
       process manager.

       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.

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
                     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



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PIPE(8)                                                   PIPE(8)


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

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

              ${recipient}
                     This macro expands to the complete recipient
                     address.   A command-line argument that con-
                     tains ${recipient} expands into as many com-
                     mand-line arguments as there are recipients.

              ${sender}
                     This macro expands to  the  envelope  sender



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PIPE(8)                                                   PIPE(8)


                     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
       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
       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.



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PIPE(8)                                                   PIPE(8)


       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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