there are a couple of ways to reduce your spam in general.
We run our own mail server and use the black hole lists to automatically block known spammers, this blocks most of the habitual spammers. the ones who do get through, like your guy, you can write the program he is spmming which is
[email protected]
also view his header and write to the ISP where he is mailing from and to who ever is hosting his site, include the spam he sent and that he have tried to get it to stop.