Mail delivery system error

Just the other day I started receiving numerous emails with Delivery status notification failed. It's the same message you get when you try to send an email to an incorrect email address.

However, I do not recognize any of the to recipients and I keep getting them. I can deal with deleting them one at a time but during the night I get approx 90 notices.

Any idea on how to get rid of them? I contatced Comcast and Norton and they have no solution.

Any advice given would be appreciated. Thanks!

At work last week we started noticing them on the 1st of September. By Friday the 3rd we had gotten well over 10,000. The guys doing it are dumbasses, on about half the emails they send out, the spyware attachment isn't even included!