LMTPD(8)

📦
version 3.12.3 · 6 versions
, in ubuntu stonking

💌 LMTPD(8) — Cyrus IMAP, bestie edition

okay so this is the lmtpd page from the Cyrus IMAP docs, section 8 (that's the "admin commands" section, iykyk). It's the LMTP server process. Sit down, grab a strawberry ✨, we're gonna get you fully caught up. 🍓

✨ NAME ✨

lmtpd — Cyrus IMAP documentation, and also: the LMTP server process. That's the whole vibe. 👑

🌸 SYNOPSIS 🌸

lmtpd [ -C config-file ]  [ -U uses ] [ -T timeout ] [ -D ]
    [ -H ] [ -a ]

🦋 DESCRIPTION 🦋

so lmtpd is an LMTP server and its whole job — its main character moment — is delivering mail into the IMAP mailstore. 💖

It reads commands on its standard input and it replies on its standard output. That's the whole conversation.

⚠️ okay real talk for a sec: it MUST be invoked by master(8), with those descriptors attached to a remote client connection. Not optional. Not a suggestion. MUST. That's the rule, periodt. 💅

And like every good little daemon, lmtpd reads its configuration options out of the imapd.conf(5) file — unless you tell it otherwise with -C. 🙈

💅 OPTIONS 💅

  • -C config-file — use the config file config-file you specify instead of the default imapd.conf(5). Not like other girls (files). ✨
  • -U uses — the max number of times this process should be reused for new connections before it shuts down. Default is 250. She has a limit, and honestly? valid. 🫶
  • -T timeout — how many seconds the process will wait for a new connection before shutting down. Lowkey important: a value of 0 (zero) disables the timeout entirely. Default is 60.
  • -D — run the external debugger specified in debug_command. 🔍
  • -H — tells lmtpd to expect a HAProxy protocol header from the sender. ✨
  • -a — preauthorize connections initiated on an internet socket instead of requiring LMTP AUTH.
🚨 bestie, listen: this should only be used for connections coming from trusted hosts. That's not me being dramatic, that's the manpage. Do not be reckless with this one. 😭

🌈 EXAMPLES 🌈

sooooo 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
    lmtpunix    cmd="lmtpd" listen="/var/run/cyrus/socket/lmtp" prefork=0 maxchild=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
}

ate that whole config block, no crumbs. 🔥

🎀 FILES 🎀

  • /etc/imapd.conf

💜 SEE ALSO 💜

go read those next, bestie, they're the lore. 🧚

⭐ AUTHOR ⭐

The Cyrus Team, Nic Bernstein (Onlight). iconic. 👑

1993–2026, The Cyrus Team

💖 and that's the whole page!! this was version 3.12.3, dated Jul 15, 2026, from the Cyrus IMAP manual. slay, go deliver some mail, ily 🫶✨

📦 where this page comes from