Whatever mode of operation you choose for each individual host, you have to make sure you have the following entry in your /etc/services file:
smtp 25/tcp # Simple Mail Transfer ProtocolThis defines the TCP port number that smail should use for SMTP conversations. 25 is the standard defined by the Assigned Numbers RFC.
When run in daemon mode, smail will put itself in the background, and wait for a connection to occur on the SMTP port. When a connection occurs, it forks and conducts an SMTP conversation with the peer process. The smail daemon is usually started by invoking it from the rc.inet2 script using the following command:
/usr/local/bin/smail -bd -q15mThe -bd flag turns on daemon mode, and -q15m makes it process whatever messages have accumulated in the message queue every 15 minutes.
If you want to use inetd instead, your /etc/inetd.conf file should contain a line like this:
smtp stream tcp nowait root /usr/sbin/smtpd smtpdsmtpd should be a symbolic link to the smail binary. Remember you have to make inetd re-read inetd.conf by sending it a HUP signal after making these changes.
Daemon mode and inetd mode are mutually exclusive. If you run smail in daemon mode, you should make sure to comment out any line in inetd.conf for the smtp service. Equivalently, when having inetd manage smail, make sure that rc.inet2 does not start the smail daemon.