Mega spam swarm

I've been getting so much spam from what is obviously a BOT making up bogus addresses (as many as 10 a day for the same SPAM) that my blacklist is full so any and everything new now gets through. I'd like to set up a whitelist (or at a minimum a blacklist able to block domains vice individual addresses) so I can control the SPAM I'm getting. Currently I am out of options other than moving from COX.