Yahoo Messenger SUCKS

I use Trillian for all of my IM needs. It's great. No complaints there. I hate Yahoo Messenger - in case you couldn't tell! LOL I get CONSTANT spam via YM. And I can't figure out how to stop it. I block it when it comes through, but I don't want it in the first place. I'd like to be able to change YM so all I get are IMs from people on my contact list. There has GOT to be a way to do that, but I have no idea how. So, I decided to nix it all. No more YM for me. I've got AIM, MSN Messenger, and ICQ. I think I'll be OK! ;-)