Ask Slashdot: How Effective Is Your ISP's Spam Filter?

An anonymous reader writes with the question in the title: does your ISP do a decent job culling spam? The reason I'm asking is that my ISP is Verizon and the Verizon spam filter is next to useless. It only blocks 15% of spam while also blocking 5% of legitimate emails. I've tried calling Verizon support a couple of times and the experience is about as pleasant and productive as banging my head on a wall. At this point I think my best move is to change ISP, but before I go around changing my email address at probably dozens of web sites I'd like to be sure that a new ISP would actually be better.