In my Gmail account, as of yesterday I was getting maybe 7 messages that were SPAM per day. This morning I had over 300. It's weird though because almost all of them were "delivery failure notifications" or some other kind of email status reports. Looks like one huge block of fake messages that didn't get through that I am somehow being notified of.
No matter, just deleted them all. Gmail does filter pretty well, so only a couple made it to my inbox.