Someone posted with a similar concern, this past August. The thread is definitely worth reading. Especially a post by one of our moderators, MarkFlax. He lists some good points, to keep yourself out of trouble.
I also posted in the same thread, with a couple of articles, which might be worth noting.
"Viral Irony: The Most Common Cause of Corruption
"#3. Turn off email scanning in your antivirus software"
Best of luck..
I don't understand how avira can be so highly recommended if it doesn't scan email.