When Delta9 is next online he can remove the posts and delete the account, unfortunately he's a bit busy with a new marriage and business to get online much at the moment. Perhaps he could consider giving one of the more regular visitors the power to deal with this type of spam attack, as it is becoming somewhat tedious?
By blocking the address from which it's sent, as with spam mail? It may be getting through as each script is slightly different (eg. this one says 'I am very angry' - a new piece added to bypass the usual spam recognition?). A job for the boss. I'm guessing it can't be so difficult to prevent this kind of thing - Canalworld and other forums I look at seem unaffected by this sort of thing.