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.
       Message  attributes  such  as  sender  address,  recipient
       address  and  next-hop  host name can be specified as com-
       mand-line macros that are  expanded  before  the  external
       command is executed.
       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=BDFORhqu.> (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.
              D      Prepend a "Delivered-To: recipient"  message
                     header  with the envelope recipient address.
                     Note: for this to work, the transport_desti-
                     nation_recipient_limit must be 1.
              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" mes-
                     sage header with the  recipient  address  as
                     given  to  Postfix.  Note: for this to work,
                     the    transport_destination_recipient_limit
                     must be 1.
              R      Prepend  a  Return-Path: message header with
                     the envelope sender address.
              h      Fold the command-line $recipient domain name
                     and  $nexthop host name to lower case.  This
                     is recommended for delivery via UUCP.
              q      Quote white space and other special  charac-
                     ters in the command-line $sender and $recip-
                     ient 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  command-line  recipients by the
                     Postfix sendmail mail submission command.
                     The q flag affects  only  entire  addresses,
                     not the partial address information from the
                     $user, $extension or  $mailbox  command-line
                     macros.
              u      Fold  the  command-line  $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 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 (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 \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.
                     This information is modified by the  u  flag
                     for case folding.
              ${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 recipients.
                     This information is modified by the  u  flag
                     for case folding.
              ${nexthop}
                     This macro expands to the next-hop hostname.
                     This information is modified by the  h  flag
                     for case folding.
              ${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.
                     This information  is  modified  by  the  hqu
                     flags for quoting and case folding.
              ${sender}
                     This  macro  expands  to the envelope sender
                     address.
                     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 recipients.
                     This information is modified by the  u  flag
                     for case folding.
       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
       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 pipe delivery
              agent.
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
                                                          PIPE(8)