You too can be a spammer!

Freeware called greylisting, when run on an email server (like I do) cuts almost all spamming out without even having to know the content. It sends a retry message to the sender and waits for a set delay. Spammers always move on and they don't retry. So far this has been working great for a few years.
I don't trust Google enough to have them house my email in their database.