use Gmail with your domain!
I've had this problem too, with hundreds of spam messages a day... I just point my domain's catchall autoforwarder to gmail. I've had to set up a few manual rules for those that "slip through" but its very good for filtering.
Another tip for people with their own domains is to use the "catchall", and register on websites using an address unique to the service. Then you can very easily see who sells your email address to someone else.
I now only get about 10 a day tops, using this method, which is much better than 400+ spams to wade through - it also helps other Gmail users at the same time as Google's systems stands more chance of recognising it as spam as other users might recieve it at a similar time.
Its always interesting to see who sells your data too..
The only real downside of this method is the catchall makes anything arrive, including randomly generated account names...