I can get my email messages scanned by Avast Mail Shield.
I can send and receive email, but they don't seem to be seen by the resident scanner, evven if I setup Wingat POP and SMTP services using ports 110 and 25.
Even looking at received messages headers I found that they haven't been scanned:
X-Antivirus: avast! (VPS 0447-1, 19/11/2004), Outbound message
X-Antivirus-Status: Not-Tested
X-Antivirus: avast! (VPS 0447-1, 19/11/2004), Inbound message
X-Antivirus-Status: Not-Tested