lmtpd - Cyrus IMAP documentation

       The Cyrus Team, Nic Bernstein (Onlight)

       1993–2025, The Cyrus Team

3.10.2                                            Jun 27, 2025                                          LMTPD(8)

lmtpd  is an LMTP server used to deliver mail to the IMAP mailstore.  It accepts commands on its standard
       input and responds on its standard output. It  MUST  be  invoked  by  master(8)  with  those  descriptors
       attached to a remote client connection.

       lmtpd reads its configuration options out of the imapd.conf(5) file unless specified otherwise by -C.

lmtpd is commonly included in the SERVICES section of cyrus.conf(5) like so:

          SERVICES {
              imap        cmd="imapd -U 30" listen="imap" prefork=0
              imaps       cmd="imapd -s -U 30" listen="imaps" prefork=0 maxchild=100
              lmtpunixcmd="lmtpd"listen="/var/run/cyrus/socket/lmtp"prefork=0maxchild=20
              sieve       cmd="timsieved" listen="sieve" prefork=0
              notify      cmd="notifyd" listen="/var/run/cyrus/socket/notify" proto="udp" prefork=1
              httpd       cmd="httpd" listen=8080 prefork=1 maxchild=20
          }

       /etc/imapd.conf

       lmtpd - Cyrus IMAP documentation

       LMTP server process

-Cconfig-file
              Use the specified configuration file config-file rather than the default imapd.conf(5).

       -Uuses
              The  maximum  number  of times that the process should be used for new connections before shutting
              down.  The default is 250.

       -Ttimeout
              The number of seconds that the process will wait for a new connection before shutting down.   Note
              that a value of 0 (zero) will disable the timeout.  The default is 60.

       -D     Run external debugger specified in debug_command.

       -a     Preauthorize  connections  initiated  on an internet socket, instead of requiring LMTP AUTH.  This
              should only be used for connections coming from trusted hosts.

imapd.conf(5), master(8)

lmtpd [ -Cconfig-file ]  [ -Uuses ] [ -Ttimeout ] [ -D ] [ -a ]