Mail preferences rules

I'm running the latest everything on my 15-inch MBP. MySpace has divulged my email address to everyone under the sun and I've tried to delete the resulting avalanche of emails by setting a Mail Rule in Preferences. So I created a rule to delete any message that has (let's say) myspace (if that's part of my MySpace ID) in the "to" field. I'm still receiving emails addressed to myspace@mymail. Directing these emails straight to Bin is equally unsuccessful. Why?