0a6419d7__virus_filter_for_SMTP_servers__Comments
[Token] ONEX [Type] Verb [SMTP server] Sendmail - Obsolete [Comments] 
Indicates that only one mail message is coming in this connection - stops Sendmail from forking a new process (supposed to make it more efficient)
ESMTP Keywords and Verbs (commands) Defined - Fluffy the SMTPGuardDog - spam and virus filter for SMTP servers
Comments