Mail account screwed up after bouncing some spam emails back to sender

Question

Alright, so I noticed the other day that you could right click on a spam message and bounce it back so it looks like you're not a valid email address. Tried it a few times and it seemed to work ok. They always bounced back to me since it probably wasn't the spammer's actual address, but anyway.
Yesterday I bounced a few back and the "Mail delivery" messages came back like they usually do. I deleted them. They came back...many many times. Sometimes they come back as new messages, sometimes they just magically appear back in my inbox after I've moved them to the trash.
The girl I work with bounced some messages (on a G4 tower) and her Mail is doing the exact same thing. There are a bunch of other PC's in the office and their mail seems to be working fine.
Now I know this may well be a problem with Dreamhost (the hosting company), and I've put in a ticket to them, but it really worries me the way my email account is acting; like it's corrupted or something. The webmail does work, but it's waaaay slow.
It's a POP3, and I have tried rebuilding the mailbox.

Answer 1

Why do you people keep bouncing spam?
If the bounce doesn't reach the destination, it's just a waste of time and bandwith, plus a source of problems, because in all likelihood it'll be bounced back to you.
If the bounce reaches the destination, then it's even worse, because you're either (1) telling the spammer that your address is valid and that you're willing to spend time on his/her/its junk, or (2) contributing to the spammer's effort by sending his/her/its junk to the innocent whose address was stolen for sending it (and who, in turn, might end up posting in a forum such as this wondering why does he/she receive bounces for messages he/she hasn't sent).
So what exactly is the point of bouncing spam? Don't you have anything better to do with your time?
OK, enough ranting. Back to the problem, you'll have to somehow remove the offending messages from the server first. After doing that, you'll have to re-create Envelope Index. Problem is, while re-creating the index Mail may choke on the messages you couldn't delete, so either be prepared for that or perform optional steps 1 and 3:
1. (Optional, but recommended). If this is a POP account, try to find in ~/Library/Mail/POP-username@mailserver/INBOX.mbox/Messages/ the *.emlx files associated with the troublesome messages. Viewing the *.emlx files as List in the Finder showing the creation/modification date may help. Just identify them; do not get rid of them yet (you must quit Mail first).
2. Quit Mail.
3. (Optional, but recommended). If you found the troublesome *.emlx files in step 1, move them to the Trash.
4. In the Finder, go to ~/Library/Mail/. Make a backup copy of this folder, just in case something goes wrong -- e.g. by dragging it to the Desktop while holding the Option (Alt) key down.
5. Locate the Envelope Index file and move it to the Trash. If you see an Envelope Index-journal file there, delete it as well.
6. In the Finder, go to ~/Library/Mail/POP-username@mailserver/. Locate Deleted Messages.mbox, and move it to the Trash. I assume there is nothing to be preserved there.
7. Open Mail. It will tell you that your mail needs to be "imported". Click Continue and Mail will proceed to re-create Envelope Index -- Mail says it's "importing", but it just re-creates the index if the mailboxes are already in Mail 2.x format.
Note: For those not familiarized with the ~/ notation, it refers to the user's home folder, i.e. ~/Library is the Library folder within the user's home folder.