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LMTP(8)                     System Manager's Manual                    LMTP(8)

       lmtp - Postfix local delivery via LMTP

       lmtp [generic Postfix daemon options]

       The LMTP client processes message delivery requests from the queue man-
       ager. Each request specifies a queue file, a sender address,  a  domain
       or host to deliver to, and recipient information.  This program expects
       to be run from the master(8) process manager.

       The LMTP client updates the queue file and  marks  recipients  as  fin-
       ished,  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.

       The  LMTP  client  connects to the destination specified in the message
       delivery request. The destination, usually  specified  in  the  Postfix
       transport(5) table, has the form:

              Connect  to  the  local  UNIX-domain server that is bound to the
              specified pathname. If the process runs  chrooted,  an  absolute
              pathname is interpreted relative to the changed root directory.

       inet:host, inet:host:port (symbolic host)

       inet:[addr], inet:[addr]:port (numeric host)
              Connect to the specified IPv4 TCP port on the specified local or
              remote host. If no  port  is  specified,  connect  to  the  port
              defined  as  lmtp  in services(5).  If no such service is found,
              the lmtp_tcp_port configuration parameter (default value of  24)
              will be used.

              The  LMTP  client  does  not perform MX (mail exchanger) lookups
              since those are defined only for mail delivery via SMTP.

       If neither unix: nor inet: are specified, inet: is assumed.

       The LMTP client is moderately  security-sensitive.  It  talks  to  LMTP
       servers  and  to DNS servers on the network. The LMTP client can be run
       chrooted at fixed low privilege.

       RFC 821 (SMTP protocol)
       RFC 1651 (SMTP service extensions)
       RFC 1652 (8bit-MIME transport)
       RFC 1870 (Message Size Declaration)
       RFC 2033 (LMTP protocol)
       RFC 2554 (AUTH command)
       RFC 2821 (SMTP protocol)
       RFC 2920 (SMTP Pipelining)

       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.

       Depending on the setting of the notify_classes parameter, the  postmas-
       ter is notified of bounces, protocol problems, and of other trouble.

       The  following  main.cf parameters are especially relevant to this pro-
       gram. See the Postfix main.cf file for syntax details and  for  default
       values. Use the postfix reload command after a configuration change.

              Verbose  logging  level increment for hosts that match a pattern
              in the debug_peer_list parameter.

              List of domain or network patterns. When a remote host matches a
              pattern, increase the verbose logging level by the amount speci-
              fied in the debug_peer_level parameter.

              Recipient of protocol/policy/resource/software error notices.

              When this parameter includes the protocol class,  send  mail  to
              the  postmaster  with transcripts of LMTP sessions with protocol

              Do not wait for the server response after sending QUIT.

              The TCP port to be used when connecting to a LMTP server.   Used
              as backup if the lmtp service is not found in services(5).

Authentication controls
              Enable  per-session  authentication  as per RFC 2554 (SASL).  By
              default, Postfix is built without SASL support.

              Lookup tables with per-host or domain name:password entries.  No
              entry for a host means no attempt to authenticate.

              Zero or more of the following.

                     Disallow  authentication methods that use plaintext pass-

                     Disallow authentication methods that  are  vulnerable  to
                     non-dictionary active attacks.

                     Disallow  authentication  methods  that are vulnerable to
                     passive dictionary attack.

                     Disallow anonymous logins.

Resource controls
              Should we cache the connection to the LMTP  server?  The  effec-
              tiveness  of cached connections will be determined by the number
              of LMTP servers in use, and the concurrency limit specified  for
              the LMTP client.  Cached connections are closed under any of the
              following conditions:

              o      The LMTP client idle time limit is reached. This limit is
                     specified with the Postfix max_idle configuration parame-

              o      A delivery request specifies a different destination than
                     the one currently cached.

              o      The  per-process limit on the number of delivery requests
                     is reached.  This limit is  specified  with  the  Postfix
                     max_use configuration parameter.

              o      Upon  the  onset  of  another  delivery request, the LMTP
                     server associated  with  the  current  session  does  not
                     respond to the RSET command.

              Limit  the number of parallel deliveries to the same destination
              via this mail delivery transport. transport is the name  of  the
              service  as  specified in the master.cf file.  The default limit
              is taken from the default_destination_concurrency_limit  parame-

              Limit  the  number  of  recipients per message delivery via this
              mail delivery transport. transport is the name of the service as
              specified  in  the  master.cf  file.  The default limit is taken
              from the default_destination_recipient_limit parameter.

              This parameter becomes significant if the LMTP  client  is  used
              for  local delivery.  Some LMTP servers can optimize delivery of
              the same message to multiple recipients. The default  limit  for
              local mail delivery is 1.

              Setting  this parameter to 0 will lead to an unbounded number of
              recipients per delivery.  However, this could be risky since  it
              may  make  the machine vulnerable to running out of resources if
              messages are encountered with an inordinate  number  of  recipi-
              ents.  Exercise care when setting this parameter.

Timeout controls
       The  default  time unit is seconds; an explicit time unit can be speci-
       fied by appending a one-letter suffix to  the  value:  s  (seconds),  m
       (minutes), h (hours), d (days) or w (weeks).

              Timeout for opening a connection to the LMTP server.  If no con-
              nection  can  be  made  within  the  deadline,  the  message  is

              Timeout  for  sending  the  LHLO  command, and for receiving the
              server response.

              Timeout for sending the MAIL FROM command, and for receiving the
              server response.

              Timeout  for  sending the RCPT TO command, and for receiving the
              server response.

              Timeout for sending the DATA  command,  and  for  receiving  the
              server response.

              Timeout for sending the message content.

              Timeout  for  sending  the  "."  command,  and for receiving the
              server response. When no response  is  received,  a  warning  is
              logged that the mail may be delivered multiple times.

              Timeout  for  sending  the  RSET  command, and for receiving the
              server response.

              Timeout for sending the QUIT  command,  and  for  receiving  the
              server response.

       bounce(8) non-delivery status reports
       local(8) local mail delivery
       master(8) process manager
       qmgr(8) queue manager
       services(5) Internet services and aliases
       spawn(8) auxiliary command spawner
       syslogd(8) system logging

       The Secure Mailer license must be distributed with this software.

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

       Alterations for LMTP by:
       Philip A. Prindeville
       Mirapoint, Inc.

       Additional work on LMTP by:
       Amos Gouaux
       University of Texas at Dallas
       P.O. Box 830688, MC34
       Richardson, TX 75083, USA