I’m running Avast 4.1 and have also run a couple of stand alone virus scrubbers. Although no virus is detected on my computer, I’m still getting tons of infected emails. They always have a subject like “Abort Notice” “Returned Mail” or “Virus Notice” and sometimes, an
Hi,
almost all of us are getting tons of these infected mails. It’s because your e-mail address is possibly in an address book of a person infected by this virus (or at least such a person got an e-mail from you in the past).
Other scenarios are possible as well. The way viruses seek for the e-mail addresses is sometimes quite complicated.
Anyway, there is not much you can do about this… :-
Just make sure you don’t get infected - but that’s what you have avast for… 
Hope this helps,
Vlk
Did you ever or do you still post in newsgroups with that Emailadress? Swen gets his Emailadresses from newsgroups, too! I has the advantage that my Mailprovider offers a good Set of Filtersetting, so i did not recieve any Swen for 10 days right now. The first three days my Mailaccount was spammed with 20 MB of Swens per day! 
Swen prevention and cure
Yet another Internet virus pretending to be a patch from Microsoft is spreading quickly on the Internet. Swen (w32.swen@mm, also known as Gibe) uses the subject line to entice Windows users to open the attachment. In some cases, the virus will execute automatically. The virus attempts to kill all antivirus and personal firewall apps running on the infected machine.