LMTP(8) LMTP(8)
NAME
lmtp - Postfix local delivery via LMTP
SYNOPSIS
lmtp [generic Postfix daemon options]
DESCRIPTION
The LMTP client processes message delivery requests from
the queue manager. Each request specifies a queue file, a
sender address, a domain or host to deliver to, and recip-
ient information. This program expects to be run from the
master(8) process manager.
The LMTP client updates the queue file and marks recipi-
ents 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) dae-
mon 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:
unix:pathname
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 spec-
ified local or remote host. If no port is speci-
fied, connect to the port defined as lmtp in ser-
vices(4). 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.
SECURITY
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.
STANDARDS
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)
DIAGNOSTICS
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.
Depending on the setting of the notify_classes parameter,
the postmaster is notified of bounces, protocol problems,
and of other trouble.
BUGS
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
debug_peer_level
Verbose logging level increment for hosts that
match a pattern in the debug_peer_list parameter.
debug_peer_list
List of domain or network patterns. When a remote
host matches a pattern, increase the verbose log-
ging level by the amount specified in the
debug_peer_level parameter.
error_notice_recipient
Recipient of protocol/policy/resource/software
error notices.
notify_classes
When this parameter includes the protocol class,
send mail to the postmaster with transcripts of
LMTP sessions with protocol errors.
lmtp_skip_quit_response
Do not wait for the server response after sending
QUIT.
lmtp_tcp_port
The TCP port to be used when connecting to a LMTP
server. Used as backup if the lmtp service is not
found in services(4).
Authentication controls
lmtp_sasl_auth_enable
Enable per-session authentication as per RFC 2554
(SASL). By default, Postfix is built without SASL
support.
lmtp_sasl_password_maps
Lookup tables with per-host or domain name:password
entries. No entry for a host means no attempt to
authenticate.
lmtp_sasl_security_options
Zero or more of the following.
noplaintext
Disallow authentication methods that use
plaintext passwords.
noactive
Disallow authentication methods that are
vulnerable to non-dictionary active attacks.
nodictionary
Disallow authentication methods that are
vulnerable to passive dictionary attack.
noanonymous
Disallow anonymous logins.
Resource controls
lmtp_cache_connection
Should we cache the connection to the LMTP server?
The effectiveness 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 parameter.
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 configu-
ration parameter.
o Upon the onset of another delivery request,
the LMTP server associated with the current
session does not respond to the RSET com-
mand.
transport_destination_concurrency_limit
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
parameter.
transport_destination_recipient_limit
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. How-
ever, 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 recipients. Exercise care when setting this
parameter.
Timeout controls
The default time unit is seconds; an explicit time unit
can be specified by appending a one-letter suffix to the
value: s (seconds), m (minutes), h (hours), d (days) or w
(weeks).
lmtp_connect_timeout
Timeout for opening a connection to the LMTP
server. If no connection can be made within the
deadline, the message is deferred.
lmtp_lhlo_timeout
Timeout for sending the LHLO command, and for
receiving the server response.
lmtp_mail_timeout
Timeout for sending the MAIL FROM command, and for
receiving the server response.
lmtp_rcpt_timeout
Timeout for sending the RCPT TO command, and for
receiving the server response.
lmtp_data_init_timeout
Timeout for sending the DATA command, and for
receiving the server response.
lmtp_data_xfer_timeout
Timeout for sending the message content.
lmtp_data_done_timeout
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.
lmtp_rset_timeout
Timeout for sending the RSET command, and for
receiving the server response.
lmtp_quit_timeout
Timeout for sending the QUIT command, and for
receiving the server response.
SEE ALSO
bounce(8) non-delivery status reports
local(8) local mail delivery
master(8) process manager
qmgr(8) queue manager
services(4) Internet services and aliases
spawn(8) auxiliary command spawner
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
Alterations for LMTP by:
Philip A. Prindeville
Mirapoint, Inc.
USA.
Additional work on LMTP by:
Amos Gouaux
University of Texas at Dallas
P.O. Box 830688, MC34
Richardson, TX 75083, USA
LMTP(8)