0a6419d7__virus_filter_for_SMTP_servers__Comments
[Token] X-EXPS [Type] Verb [Reference] Microsoft [SMTP server] Microsoft Exchange Server [Comments] 
Microsoft version of AUTH. Seems to work the same way. If accepted challenge/response pairs are sent 1 or more times.
ESMTP Keywords and Verbs (commands) Defined - Fluffy the SMTPGuardDog - spam and virus filter for SMTP servers
Comments