I can't recall if this article from The Register got mentioned here or not:
Click here to become infected By John Leyden Published Wednesday 22nd September 2004 09:15 GMT Users should be wary of pressing the 'click here to remove' link on spam messages because it serves to confirm to spammers that junk mail messages are being read. Such email addresses can be sold at a premium to other spammers. That's reason enough to simply delete spam messages, but a junk mail message doing the rounds today provides an even more compelling reason. Selecting the 'click here to remove' link on messages blocked by MessageLabs today triggers an attempt to load malicious code onto potentially vulnerable Windows PC. http://www.theregister.co.uk/2004/09/22/opt-out_exploit/ Not sure about the rest of you but I have stopped advising my users to click on those links anway. I just assume that they're used more as address confirmation than for really opting out... -Joe