Technical Q & A: email system infected?
People are receiving spam from my email - is my computer infected?
Maybe. Make sure that your computer's anti-virus software and virus signatures are up-to-date and then do a full scan (this might take a few hours). A long time ago in Internet time (that is, a few years ago in real time!) the vast majority of these problems were indeed caused by viruses on your computer.
Why do spammers or virus writers want to use my email address as the "From" address?
It is trivial to forge an email's return address to something other than the real sender; the hard part is to get people to open the spam or virus. Evil people want to forge the email's "return" address to your friends because the chances are higher that the email will be opened. How many times have your received a "greeting card" from a friend and opened it without thinking about it? You might not want to do that in the future now that you know the game these people play! Even if they can't get your mailing list, they might use your email address to help bypass spam filters that check to see if a return address is "real".
So... how do spammers get my email address and those of my friends?
With the increasing sophistication of antivirus software preventing most viruses from becoming very widespread, now days there are two popular schemes used by spammers to get your email address and your mailing list.