According to this article: MSNBC - New reason to avoid 'unsubscribe' links, some spammers are sneaking a secret code into the unsubscribe link that may turn you into a spammer as well. Please note that this is being done by SPAMMERS, and not by legitimate companies.
It's always been a bad idea to click the "unsubscribe" link in spam (it lets the spammer know that your email address is live) -- so just delete them instead or report it via spamcop.
Posted by Lee at October 21, 2004 01:54 PM