This technique also allows you to figure out which people/companies have had their systems hacked or had a virus.
As I've written before, listserv addresses often get spam/junk because they get posted to the internet by some person who thinks they're doing people a favor by archiving emails without stripping the "from" addresses off them. (i.e., the "redhat-sound" mailing list address I used is a spam target).
Today I add a new company to the "hacked" list.
Saunders, USA. While they manufacture great hard cases for PDA's, the security on their customers data is not nearly as strong.
Saunders, USA: You're getting a bonus :-p because your customer service e-mail address just bounced.
Hacked, virused, trojaned:
We're About 9
EDIT: It seems like this is another "Person stupid enough to click on an e-mail attachment" virus. Of course, it just happened to be someone at Saunders, USA who was the one dumb enough to do it.