Be
very careful with this virus / worm. It puts in a 'from' address that looks familiar - possibly similar to someone you email from time to time or someone who contacted you in the past, etc. It doesn't always show up as having an attachment (don't know how they do that). It often has the subject line as Hi, or Test, or even more scary "Mail Delivery Failure" (and many other similar messages).
At work yesterday we had 86 hits from this virus in one hour!!!!! It has subsided a little today, but not a lot! Many years ago we put the first email address in our address books on each computer as
000@000.com (zero's). If we were ever infected inadvertantly, in theory it should stop it emailing everyone in our address books, as it would go to the first, which is non-existant (I think!) and get stuck.