I’ve now added some Realtime BlockLists (RBLs) to Spam Karma 2, to further reduce the chances of seeing ugly spam on this site. Basically the way it works is that the IP of a comment is sent to the RBL server, which then responds telling the requester (SK2 in this case) whether it is on the spam list or not. Many of them are aimed at e-mail spam (which the system was developed for), but many (e.g. those listing open proxies) are just as useful against comment spam.