0a6419d7__virus_filter_for_SMTP_servers__Comments
[Token] X=EXPS= [Type] Keyword [SMTP server] Microsoft Exchange Server [Comments] 
This seems to indicate support for the X-EXPS parameter with the MAIL verb.
ESMTP Keywords and Verbs (commands) Defined - Fluffy the SMTPGuardDog - spam and virus filter for SMTP servers
Comments