This is how it was explained to me when someone receives a virus and it points to your computer. I had that happen to me just yesterday. My computer is 100% clean and I did not even have my computer turned on until supper time and a virus was supposedly sent from me that morning. So, I hope for all of you this explanation will be informative. The procedures followed in the transport of email over the Internet in theory allow for the origin and the progress of email to be traced. When an email leaves your PC it contains in its headers certain information derived from the settings on your email application. This includes the originator's, identity, address and date and time of creation. Emails are then handed off from one server to another as they move from source to destination. Each server adds in the header the IP Address of the server it received the email from, the server's name, and the date and time. Current virus writers are crafty SOBs who want to foul things up real good to foil tracking and seduce recipients into believing the forgery is genuine so they have dicked around with these procedures. The Bagle virus, for example, contains its own email application (called an SMTP engine) that allows it to write and send email without using its host's email application. It is possible for the virus to forge headers and to send it to servers of its choosing. The information it needs for its forgeries is gleaned from files it scans on its host. For example, it will create an email on A's machine that looks like it came from C and it is addressed to B. B gets the email observes that it is "from" C, blames C while A is oblivious to the whole thing and whose PC sends out a flurry of new forgeries every time A turns on his/her diseased PC. The deception goes very deep. The scumbags have located email servers that are not properly set up to scan for viruses, nor screen out unauthorized traffic, and accordingly written right into the virus instructions to send the email to one of these servers. I have seen examples of Bagle viruses that relay thier virus email through a server in Argentina. So if you see a virus email that looks like it came fom somebody called Peaches4Ul, it probably didn't. Furthermore, if you get an email with attachments from your mother do not click on it. Call her up and ask her about it first.