Server blacklists tend to go bad, because the power they confer corrupts the people running them. They turn into vigilantes and start blacklisting innocent servers. The most notorious example is the MAPS RBL. I used to recommend Spamhaus's SBL as an alternative, but it seems even this previously upstanding service is going the way of other blacklists. This email I received recently sounds eerily familiar: You described the Spamhaus SBL as "responsible". I beg to differ. I recently noticed that my IP range, ----, was blacklisted on the Spamhaus SBL. I inquired as to the reason for that, and they informed me that my data center, ----, had hosted some spammers in the past. Their entire network, subnet mask ----, is blacklisted. I explained to them that while I can't vouch for the rigor with which ----'s AUP is enforced, that I am innocent in the matter, and requested that my four IPs be whitelisted. I got back a rather rude response along the lines of "no we won't, because it's your fault for using an ISP that tolerates spam". I don't find that answer terribly responsible. This is bad news, not just for the SBL but for the whole idea of blacklists. The SBL was started with the explicit aim of avoiding the kinds of abuses that had tainted other blacklists. So if even they are going the way of the MAPS RBL, one has to assume that every blacklist will, eventually.