This might be old news and perhaps I'm the only one only finding this out now... or perhaps this is a bad idea for some reason, but I thought I'd share this for those of you who have your own domains.
Came across this by accident while googling MX records (since I don't know too much about DNS, etc.)
I did this two days ago and haven't received one spam message on our domain since. Before our junk mail folder was filled up on a daily basis. In our case I simply created 3 MX records. The first and last ones are fake and the middle one is the correct one.