STARTTLS and MTAs
Under most distributions of Linux, Sendmail and Postfix RPMs are not enabled for SASL authentication. As a result, our instructions show how to build Sendmail and Postfix manually with support for SMTP AUTH/STARTTLS.
qmail supports only basic SMTP functions with the base distribution, so you must use a third-party patch in order to get the SMTP AUTH/STARTTLS functionality. We use netqmail-1.05, which has a number of patches for features that don’t exist in the base qmail version, including SMTP AUTH/STARTTLS.
Our approach is to use the Cyrus SASL 2.1.8 SMTP AUTH/STARTTLS package for most of the underlying work. The appropriate hooks in the covered MTAs will be activated to support the Cyrus SASL implementation. ...