SMTP Authentication is intended to be used in an environment where you need to prevent untrusted machines from using your mail servers as sending machines. Such environments generally have things such as laptops or PDA's being used for e-mail purposes.

Once you have SMTP Auth properly installed, you will need to add entries into the access database to fully utilize it.

Authinfo entries can contain an IP address, a hostname or a domain name. When Sendmail makes a connection with a host, and the other host matches an entry in the access database to use SMTP Authentication, then Sendmail will ask the other host to authenticate itself.

Authentication is done by either supplying a username and password or by supplying an authentication id and password. Consult either the bat book or http://asg.web.cmu.edu/sasl/ for more information.

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