SMTPD(8) | System Manager's Manual | SMTPD(8)

# NAME

`smtpd` — Simple Mail Transfer Protocol (SMTP) daemon

# SYNOPSIS

`smtpd` | [`-dFhnv`] [`-D` macro=value] [`-f` file] [`-P` system] [`-T` trace]

# DESCRIPTION

`smtpd` is a Simple Mail Transfer Protocol (SMTP) daemon which can be used as a machine's primary mail system. `smtpd` can listen on a network interface and handle SMTP transactions; it can also be fed messages through the standard sendmail(8) interface. It can relay messages through remote mail transfer agents or store them locally using either the mbox or maildir format. This implementation supports SMTP as defined by RFC 5321 as well as several extensions. A running `smtpd` can be controlled through smtpctl(8).

The options are as follows:

`-D` macro=value
  Define macro to be set to value on the command line. Overrides the definition of macro in the configuration file.
`-d`
  Do not daemonize. If this option is specified, `smtpd` will run in the foreground and log to stderr.
`-F`
  Do not daemonize. If this option is specified, `smtpd` will run in the foreground and log to syslogd(8).
`-f` file
  Specify an alternative configuration file.
`-h`
  Display version and usage.
`-n`
  Configtest mode. Only check the configuration file for validity.
`-P` system
  Pause a specific subsystem at startup. Normal operation can be resumed using smtpctl(8). This option can be used multiple times. The accepted values are:

  mda
    Do not schedule local deliveries.
  mta
    Do not schedule remote transfers.
  smtp
    Do not listen on SMTP sockets.
`-T` trace
  Enables real-time tracing at startup. Normal operation can be resumed using smtpctl(8). This option can be used multiple times. The accepted values are:

  - imsg
  - io
  - smtp (incoming sessions)
  - filters
  - transfer (outgoing sessions)
  - bounce
  - scheduler
  - expand (aliases/virtual/forward expansion)
  - lookup (user/credentials lookups)
  - stat
  - rules (matched by incoming sessions)
  - mproc
  - all
`-v`
  Produce more verbose output.

# FILES

/etc/mail/mailname
  Alternate server name to use.
/etc/mail/smtpd.conf
  Default `smtpd` configuration file.
/var/run/smtpd.sock
  UNIX-domain socket used for communication with smtpctl(8).
/var/spool/smtpd/
  Spool directories for mail during processing.
~/.forward
  User email forwarding information.

# SEE ALSO

forward(5), smtpd.conf(5), mailwrapper(8), smtpctl(8)

# STANDARDS

J. Klensin, Simple Mail Transfer Protocol, RFC 5321, October 2008.

# HISTORY

The `smtpd` program first appeared in OpenBSD 4.6.

March 2, 2023 | Debian