I'm using MS Outlook with POP3 (TCP 110) to receive mail. I have Antivirus and Antispyware policy configured for Internet E-mail Auto-protect and assigned to computers.
I'm not saying this is the cause, but is there some reason you're not using the Outlook scanner?
According to "About Auto-Protect and email scanning" (link is below), email scanning is not available for 64-bit clients for 11.x. It also says:
For scans of Lotus Notes and Microsoft Exchange email, Auto-Protect scans only the attachments that are associated with email.
For Internet email scanning of the messages that use the POP3 or SMTP protocols, Auto-Protect scans the following items:
- The body of the message
- Any attachments to the message
See the following:
About Auto-Protect and email scanning
http://www.symantec.com/docs/TECH95093
You may want to consider Mail Security for Microsoft Exchange.
sandra