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 com-
       mand-line macros that are  expanded  before  the  external
       command is executed.

       The  pipe(8)  daemon updates queue files and marks recipi-
       ents as finished, 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  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  Delivered-to:  or  X-Original-To:   message
       header.

       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:

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

              This feature is available as of Postfix 2.3.

       directory=pathname (optional)
              Change  to the named directory before executing the
              external command.  The directory must be accessible
              for the user specified with the user attribute (see
              below).    The   default   working   directory   is
              $queue_directory.   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 recognized: \a \b \f \n \r  \t
              \v \ddd (up to three octal digits) and \\.

       flags=BDFORXhqu.> (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  (see  SIN-
                     GLE-RECIPIENT DELIVERY above for details).

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

              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  (see  SINGLE-RECIPIENT DELIVERY
                     above for details).

                     This feature is available as of Postfix 2.0.

              R      Prepend  a  Return-Path: message header with
                     the envelope sender address.

              X      Indicate that the external command  performs
                     final  delivery.  This flag affects the sta-
                     tus reported in "success" DSN (delivery sta-
                     tus  notification)  messages, and changes it
                     from "relayed" into "delivered".

                     This feature is available as of Postfix 2.5.

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

              q      Quote  white space and other special charac-
                     ters in the  command-line  $sender,  $origi-
                     nal_recipient  and $recipient address local-
                     parts (text to the left of the right-most  @
                     character),  according to an 8-bit transpar-
                     ent 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(1) 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  $original_recipient
                     and $recipient address  localpart  (text  to
                     the  left  of the right-most @ character) to
                     lower case.  This is recommended for  deliv-
                     ery 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.

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

              The null sender replacement text may be empty; this
              form  is  recommended for content filters that feed
              mail back into Postfix. The empty sender address is
              not  affected  by the q flag for address quoting in
              command-line arguments.

              Caution: a null sender address is easily mis-parsed
              by  naive  software.  For example, when the pipe(8)
              daemon executes a command such as:

                  Wrong: 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 $sender as an argument by itself:

                  Right: command -f $sender -- $recipient

              This feature is available as of Postfix 2.3.

       size=size_limit (optional)
              Don't deliver messages that exceed this size  limit
              (in bytes); return them to the sender instead.

       user=username (required)

       user=username:groupname
              Execute  the  external command with the user ID and
              group ID 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.

       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.

              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 net-
                     work address.

                     This feature is available as of Postfix 2.2.

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

                     This feature is available as of Postfix 2.2.

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

                     This feature is available as of Postfix 2.2.

              ${client_port}
                     This  macro expands to the remote client TCP
                     port number.

                     This feature is available as of Postfix 2.5.

              ${client_protocol}
                     This macro expands to the remote client pro-
                     tocol.

                     This feature is available as of Postfix 2.2.

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

                     This information is modified by the  h  flag
                     for case folding.

                     This feature is available as of Postfix 2.5.

              ${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 to 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.

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

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

                     This  information  is  modified  by  the hqu
                     flags for quoting and case folding.

                     This feature is available as of Postfix 2.5.

              ${recipient}
                     This macro expands to the complete recipient
                     address.

                     A  command-line   argument   that   contains
                     ${recipient} expands to 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 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.

              ${sasl_sender}
                     This  macro  expands to the SASL sender name
                     (i.e. the  original  submitter  as  per  RFC
                     4954)  in  the  MAIL  FROM  command when the
                     Postfix SMTP server received the message.

                     This feature is available as of Postfix 2.2.

              ${sasl_username}
                     This  macro expands to the SASL user name in
                     the  AUTH  command  when  the  Postfix  SMTP
                     server received the message.

                     This feature is available as of Postfix 2.2.

              ${sender}
                     This macro expands to  the  envelope  sender
                     address. By default, the null sender address
                     expands  to  MAILER-DAEMON;  this   can   be
                     changed  with  the null_sender attribute, as
                     described above.

                     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.

STANDARDS
       RFC 3463 (Enhanced status codes)

DIAGNOSTICS
       Command  exit status codes are expected to follow the con-
       ventions defined in <sysexits.h>.   Exit  status  0  means
       normal successful completion.

       In the case of a non-zero exit status, a limited amount of
       command output is reported in an delivery status notifica-
       tion.   When  the  output  begins  with  a  4.X.X or 5.X.X
       enhanced status code, the  status  code  takes  precedence
       over  the  non-zero  exit  status (Postfix version 2.3 and
       later).

       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
       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 mas-
       ter.cf entry.

       transport_destination_concurrency_limit ($default_destina-
       tion_concurrency_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_destina-
       tion_recipient_limit)
              Limit  the  number of recipients per message deliv-
              ery, for delivery via  the  named  transport.   The
              limit is enforced by the Postfix 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.

              Postfix  2.4 and later support a suffix that speci-
              fies the time unit: s  (seconds),  m  (minutes),  h
              (hours), d (days), w (weeks). The default time unit
              is seconds.

MISCELLANEOUS CONTROLS
       config_directory (see 'postconf -d' output)
              The default location of  the  Postfix  main.cf  and
              master.cf configuration 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.

       delay_logging_resolution_limit (2)
              The  maximal  number  of  digits  after the decimal
              point when logging sub-second delay values.

       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  an  incoming  connection
              before terminating voluntarily.

       max_use (100)
              The  maximal  number of incoming connections that a
              Postfix daemon process will service  before  termi-
              nating voluntarily.

       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 direc-
              tory.

       recipient_delimiter (empty)
              The separator between user names and address exten-
              sions (user+foo).

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (see 'postconf -d' output)
              The  mail  system  name  that  is  prepended to the
              process name in syslog  records,  so  that  "smtpd"
              becomes, for example, "postfix/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)