smtpd - SMTP message storing daemon

smtpd[-cchrootdir][-dspooldir] [ -u user ] [ -g group ] [ -m myname ] [ -s maxsize ] [ -H ] [ -P ] [ -D ] [ -L ]

The smtpd daemon talks the Simple Mail Transfer Protocol (SMTP) with other SMTP daemons to receive mail from them, and saves it into a spool directory for later processing. It is the store portion of an SMTP store and foward proxy. The symbiotic companion program smtpfwdd is used to forward the spooled mail on to its eventual destination. smtpd is invoked from a super-server such as inetd or juniperd.

-c chrootdir

Specify a different directory to chroot to on startup than the default spool directory (/var/spool/smtpd).

This directory should be readable and writable only to the user that smtpd runs as.

-d spooldir

Specify a different spool directory within the chrooted subtree. The default is ".", making smtpd spool files to the directory it chroots itself to.

-u user

Specify a user to run as. This user must not be root but should normally be a user that is able to run sendmail and use the -f option to specify the sender of a mail message.

-g group

Specify a group to run as. Same as user above.

-H

Disable host checking against the DNS. By default smtpd checks and will complain in the syslogs if the DNS information on a host seems to indicate a possible spoof or misconfiguration.

-m myname

Specify the hostname the daemon should announce itself as. the default is whatever gethostname() returns.

-s maxsize

Specify (in bytes) the maximum size of mail message the daemon should accept. The default is not to have a maximum size.

-P

Enable paranoid mode of operation, in this mode connections are dropped from any client feeding smtpd a suspicious hostname, FROM:, or RCPT: line containing characters indicative of an attempt to do something evil, or any message headers that aren't 8bit clean. The default is to log such occuurances and substitute for the offending characters, but not drop the connection.

-D

Tells smtpd to run as a daemon, listening on port 25. The default is not to run as a daemon (i.e. it should normally be spawned from juniperd or inetd.

-L

Suppress children in daemon mode (above) from doing an openlog() call. This means your syslogs won't have pid information, but is useful if you don't want to have to set up your chroot jail for smtpd in a manner that an openlog() call will work in it.

Since sendmail is not normally running as a daemon when

using smtpd and smtpfwdd, one must use cron to periodically invoke sendmail -q so that queued messages are retried for eventual delivery.

smtpd and smtpfwdd are also available separately from Juniper under quite friendly copyright terms. It can be obtained using anonymous ftp in the directory ftp://ftp.obtuse.com/pub/smtpd

juniperd(8), smtpfwdd(8), smtpd_address_check(5)

Obtuse Systems Corporation

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