Hello!
Hoping that the spam servers will be shut down is illusionary. You could of course report it to some central ("whois" of the domain that is linked to could help) but that isn't helping much because in the time one server is shout down ten new ones are being created.
Well, the first would be upgrading to 2.6.7, teh second looking for some better solution for preventing spams. There are so many posts here in the forum (take the forum search and search after "spam"), there are many ways. I think individualisation is the best.
Regards Michael