Just a little bug.
I declared a forwarded address (see my ask in this forum)
one of the target address is on external domain and mail server.
If the message include a virus, and you have declared to notify sender or recipient in SMTP Antivirus an error occur during notification.
sender for Notification mail is "MailDaemon" which is not a valide address for an external mail server.

Suggestion : Add possibility to declare a mail account to send notifications.

"SMTPC" 852 "2004-07-14 17:28:09.296" "192.168.1.25" "SENT: MAIL FROM:<MailDaemon>"
"SMTPC" 852 "2004-07-14 17:28:09.296" "192.168.1.25" "RECEIVED: 501 unacceptable mail address"
"APPLICATION" 852 "2004-07-14 17:28:09.296" "SMTPDeliverer - Message 904: Message delivered successfully."

Or maybe just make it so the domain name is appended to the end.
IE: MailDaemon@thedomain.com
That should fix the problem as most mail servers reject mail from a sender with no domain.