I received my first ever email virus today,"Win32:Plexus [Wrm]" which avast detected but when it asked what I would like to do, it said unable to process file and did this with every option I tried.
I then clicked ok since it was all I could do and when I checked my inbox the infected message was there with a warning in the subject "VIRUS - Do Not Open".
Since it was from someone calling me Nick, which isn't my name, I wouldn't have opened it anyway but why wouldn't avast deal with it properly?
I am using Thunderbird and since I keep regular back-ups of my profile, I ended up erasing the entire "Mail" folder in my profile and replacing it with the backup, just to be safe.