[spam-stopper] competition spammers

[Michiel Dethmers]

Quite some time ago, a client was having a competition on their site,
where you could win some plane tickets to New York (this is a UK site,
so a ticket to NY is nice :-). We noticed a surge in sign ups and I
analysed it to be a "competition spammer". I wrote it up here:
http://tincan.co.uk/659/news/competition-spammers.html

Then another client had the same issue a few months later. And now I
have the third client with the same problem. And I did a check and the
Akismet API doesn't return "spam". In fact, neither does mollom, stop
forum spam or honeypot.

Now, I guess it's a bit heavy to do a whois lookup on every email, but
do you see any way to start adding these domains to your database in a
scalable way?