“Dave's Spam”

Dave Winer mentioned this morning that he received

"250 emails this morning. Only four contained content. The rest were spam and viruses."

I'd like to know how much of that email came through the Yahoo Groups that he's a member of. I'm really sick of YG! I've joined a bunch of lists hosted there in the last couple of years, but now they seem to be my single largest source of spam (either spam sent directly to the list, or spam sent to the address I used to subscribe only to that list).