I seem to have picked up a virus that is sending stuff to other people from my Yahoo account (I get the “undeliverable” messages). Is there something I can do to get this forwarding virus off of my email account?
You probably don’t have a virus. The problem is that viruses lie. The most likely scenario is that somebody who has your e-mail address (which means that you have sent that person an e-mail, or that that person has sent you an e-mail, or that someone else entirely has sent both of you an e-mail, at some point in the indeterminate past) has a virus. That person’s computer, being infected, is sending out lots and lots of virus e-mails. And those e-mails all have random addresses listed as their “from” address. Typically, these are scavenged from all e-mail addresses on the host computer, including yours. So even though you’re clean, there are a bunch of infected e-mails out there claiming that they came from you. So the mail servers on the victims’ end, being stupid, think you’re the cause, and send angry e-mails to you complaining that you’re sending out bad e-mails.
I had a problem similar to this, and it turns out it wasn’t my account or a virus. Someone who had my name in their address book had a virus that was using my address url to send emails to others. That’s why I was getting the undeliverable messages. Even though I never sent it. You get the drift. Email everyone in your address book and have them scan their systems for viruses. It should solve the problem. If not, I have no clue.
Just because you’re receiving “Mail undeliverable” messages doesn’t mean that your machine is infected. Many recent worms will forge the From: address of the messages they send out, so you are probably receiving notifications generated by mail from someone else’s computer. There isn’t much you can do except delete them.
Still, it’s a good idea to run a virus scan once in a while just to be safe.
I received a spam email to my Hotmail account recently which had been CCed to my (quite rare) first name combined with about a hundred variants on my surname. I felt kind of special. 
Well, I guess that’s good and bad news. Good that I’m not (likely) infected, bad that there’s nothing I can do about it. I think I might scrap my Yahoo account and start a new one with them, only telling a very special few about it. I have a suspect in mind who is probably lousy with viruses - he downloads everything with no discretion.
In a few cases I’ve had today, the ‘mail undeliverable’ message is in fact the message carrying the virus and isn’t a response from a mail server at all.
About half of all my Yahoo Bulk Mail (ie spam) contents (upwards of 15 a day) is this type of email. The attachment, purporting to be the returned message, is actually a virus, as **Mangetout ** says. This is how they propagate. Just hit delete.
I was having this problem with my mail.com account, and reported the undeliverable messages as spam, and the problem amazingly went away.
Is it still true that (as long as you’re not using outlook) that viruses are only in attachments, and if you don’t download anything you should be safe? I’ve gotten a number of these “undeliverable” messages lately…
The problem with just deleting them, however, is that I’m in the process of e-mailing some writers to invite them to have their stories archived/linked on my fanfic site, and some of the stories are from the 90s so I need to know if their address doesn’t work so I can try another. The “fake” ones look just like real returned e-mail 
It’s a “Joe Job”
http://www.techtv.com/news/culture/story/0,24195,3415219,00.html
No virus necessary.
Happened to me once, and after the first bunch of messages it slowed and stopped. The address is perfectly usable now.