| NAME | SYNOPSIS | DESCRIPTION | FILES | SEE ALSO | STANDARDS | HISTORY | COLOPHON | |
|  | 
SMTPD(8)                  System Manager's Manual                SMTPD(8)
       smtpd — Simple Mail Transfer Protocol (SMTP) daemon
       smtpd [-dFhnv] [-D macro=value] [-f file] [-P system] [-T trace]
       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.
       /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.
       forward(5), smtpd.conf(5), mailwrapper(8), smtpctl(8)
       J. Klensin, Simple Mail Transfer Protocol, RFC 5321, October 2008.
       The smtpd program first appeared in OpenBSD 4.6.
       This page is part of the OpenSMTPD (a FREE implementation of the
       server-side SMTP protocol) project.  Information about the project
       can be found at https://www.opensmtpd.org/.  If you have a bug
       report for this manual page, see
       ⟨https://github.com/OpenSMTPD/OpenSMTPD/issues⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://github.com/OpenSMTPD/OpenSMTPD.git⟩ on 2025-08-11.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2025-08-02.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there is
       a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org
GNU                           March 2, 2023                      SMTPD(8)