#2 Feb 14, 2009 03:06
I haven't played in the antispam space in a long long time, but I can tell you this: EVERY keyword is driven by user submissions. We used to ban specific blogspot domains until they "took over" the antispam list. It was decided to ban ".blogspot.com" so that users didn't have to have over 5000 entries.
I'm supposed to go back into that space but holy cow time-sensitive projects have me buried. If/when I do it'll be to turn it over to someone else, and they will (hopefully) follow the same criteria: if enough users report a domain frequently enough in a short enough time span it gets added. Eventually it'll get removed, but that took no one reporting it anymore.