pipe



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 external commands cannot handle more than one recipient per deliv-
       ery  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:

       directory=pathname (optional, default: $queue_directory)
              Change to the named directory before executing the external com-
              mand.  Delivery is deferred in case of failure.

              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=BDFORhqu.> (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.

                     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.

                     This feature is available as of Postfix 2.0.

              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  deliv-
                     ery via UUCP.

              q      Quote  white  space  and  other special characters in the
                     command-line $sender and  $recipient  address  localparts
                     (text to the left of the right-most @ character), accord-
                     ing 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 $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 software.

       size=size_limit (optional)
              Messages  greater  in  size  than  this limit (in bytes) will be
              bounced back to the sender.

       user=username (required)

       user=username:groupname
              The external command is executed with the rights of  the  speci-
              fied  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.

       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 is available in Postfix 2.2 and later.

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

                     This is available in Postfix 2.2 and later.

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

                     This is available in Postfix 2.2 and later.

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

                     This is available in Postfix 2.2 and later.

              ${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
                     into 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.

              ${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.

              ${sasl_method}
                     This macro expands to the SASL  authentication  mechanism
                     used during the reception of the message. An empty string
                     is passed if the message has been received  without  SASL
                     authentication.

                     This is available in Postfix 2.2 and later.

              ${sasl_sender}
                     This  macro  expands  to  the  SASL sender name (i.e. the
                     original submitter as  per  RFC  2554)  used  during  the
                     reception of the message.

                     This is available in Postfix 2.2 and later.

              ${sasl_username}
                     This  macro expands to the SASL user name used during the
                     reception of the message. An empty string  is  passed  if
                     the  message  has  been received without SASL authentica-
                     tion.

                     This is available in Postfix 2.2 and later.

              ${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 recipi-
                     ents.

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


DIAGNOSTICS

       Command  exit  status  codes  are  expected  to  follow the conventions
       defined in <sysexits.h>.

       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.


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.

       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 the next service request before exiting.

       max_use (100)
              The  maximal number of connection requests before a Postfix dae-
              mon process terminates.

       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 (postfix)
              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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