For more information on TLS/SSL and Cyrus SASL, see the following websites:
http://www.sendmail.org/~ca/email/auth.html
http://www.sendmail.org/~ca/email/starttls.html
http://docs.hp.com/en/netcom.html#Internet%20Services
http://www.sendmail.org/misc/other-non-sendmail-links.php
