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/mailname       Alternate server name to use.
       /etc/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.

Debian                                            March 2, 2023                                         SMTPD(8)