"Ignore anyone who is not on my Messenger List"

I've been getting Yahoo! Messenger spam regularly. The current version allows me to report the message as spam, and I did that on every one. Unfortunately that didn't seem to help. All of the spam similar in that it has URLs with garbage characters paired with URL characters, kind of like what happens if you view UTF-16 Unicode as ASCII. I've now reluctantly set Messenger to "Ignore anyone who is not on my Messenger List".