Vladimyr's link has since been edited - the new answer is actually confusing.
Follow this:
Right-click "a" tray icon > On-Access Protection Control > Details... >> > Internet Mail > Customize > Advanced
then: (tick) silent mode > select: general answer 'yes' (ok)
Note: The antivirus protection is still on, but not putting a pop up on screen that requires an action every time. In this mode a pop up does appear for 1-2 seconds then disappears, and deletes the virus automatically.
A very handy setting change if you receive a lot of mail, a lot of spam, and viruses.