Oddly enough, if I simply drop email addressed to my domain registration email [7] that is NOT from my registrar, then the amount of spam I receive would drop about 70%.
But frankly, with the greylisting, the spam that does get through is easy enough to deal with. And I'm the only person who uses my domain for email.
[1] I started in the web hosting business in '96 or '97 so this is pretty much old hat for me.
[2] Definition: http://projects.puremagic.com/greylisting/
[3] Software I use: http://www.x-grey.com/
[4] http://boston.conman.org/2015/04/12.1
[5] http://en.wikipedia.org/wiki/DNSBL
[6] http://boston.conman.org/2015/05/11.1
[7] Yeah, I don't bother with the privacy settings on the domain registration.