I first blogged about the ANONWHOIS blacklist back in 2010. It was very useful to identify domains were ownership information was cloaked from the public. Why? Because many of us in the anti-spam and security community think that for a domain being used for commercial purposes, it isn't right to hide who the owner is. And this obstruction to transparency is often exploited by bad guys who send spam and malware, to try to make it harder to identify them.