How do you deal with it? At the server level, or use a third party filter provider like netriplex? If you deal with it at the server level what do you use? Any off-the-shelf software or a custom/homegrown set of techniques?
At server level I have disabled email, using my ISP instead, and forwarding the messages to Gmail where most of the spam is filtered. Of course I have nobody else than myself hosted on my server.
Perhaps if you made your question clear in the first place there wouldnt be any ambiguity. You wanna know what i use to combat email spam? Well, guess what... I use a spam filter. I answered your question... So, why the hell are you giving me a red rep in which you call me names? Your upset when you ask a vague question and get a vague response. Give yourself a red rep...not me.
I like Spam Assassin, and there are several quality blacklists that you could use. Don't forget to use an open relay(proxy) blacklist too(http://www.ordb.org/). Good luck
I personally use Spamhaus and a few other blacklists I can't recall at the moment. Works pretty good though a few slip by.
Perhaps if you had bothered to read the first post before posting, you would have understood the "question" unambiguously I've disabled it as theres a bug with Plesk, spam assassin & DrWeb antivirus that keeps sending "message undeliverable mails", thousands of them continously.