That's a philosophically vexed question. AIUI, as mhurron says, what Spamhaus does is publish a list. The nominal purpose of that list is to identify spammers

That's a philosophically vexed question. AIUI, as mhurron says, what Spamhaus does is publish a list. The nominal purpose of that list is to identify spammers, so that people who wish to filter out spam can be assisted by that. People do, in fact, use that list, to filter email. The email recipient wants to be protected from spam, so the recipient's ISP attempts to perform that service, and Spamhaus contributes an opinion that the ISP takes seriously. So, in practice, if Spamhaus adds you to their list, many many users will stop seeing email from you. Spamhaus has a great deal of power to mostly-silence domains. I have no reason to believe that Spamhaus uses their power for anything other than good. But it's not quite as simple as "do they censor? no". http://en.wikipedia.org/wiki/Spamhaus http://en.wikipedia.org/wiki/Spamhaus http://en.wikipedia.org/wiki/DNSBL#Criticisms http://en.wikipedia.org/wiki/DNSBL#Criticisms