Oh crap. Someone out there is mailing a virus using my email address and there’s nothing I can do. This particular virus (klez.e) takes a random email address from the infected PC and uses that as the ‘From’ email address. This means I can look forward to a heap of people emailing me telling me I’m infected when I am not. It’s particulary galling because I update my antivirus files everyday.
More info in the ‘Notes’ section of the above site if you are interested.