From https://www.fehcom.de/qmail/smtpauth.html#PATCHES
Generic SMTP authentication for qmail-smtpd and qmail-remote.
Complies to RFC 3848 and RFC 4409.
* Provides now CRAM-MD5 authentication for qmail-remote as well.
* Fine tuning of SMTPAUTH annoncements for qmail-smtpd and
SUBMISSION support.
* Sender based authentication according to 'Mail From:' and
authenticated smarthost relaying for qmail-remote.
* Fixed bug (0.8.2): qmail-smtpd secretly allows auth even when
disabled! (tx Chris P.)
* Fixed AMD64 bug for MD5 (0.8.3) and small others (tx Alan P.)
