I first blogged about the ANONWHOIS blocking list 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.
For folks working in the deliverability realm, we used ANONWHOIS to remind clients that it is not a best practice to mask ownership info for a domain name. ISPs who notice this will often consider it suspicious, and services like the Network Abuse Clearinghouse will decline to include your domains in their database.
The ANONWHOIS website recently went offline, somewhere around the start of February, 2017. (The Internet Wayback Machine last shows the ANONWHOIS website up and running on October 2, 2016.)
I was able to contact one of the maintainers of ANONWHOIS and he confirmed for me that they have shut down for good. Sounds like ICANN policy changes over the past few years have made it harder and harder for them to adequately track information necessary to make informed decisions regarding potential entries on their list.
I am sorry to see them go, but I thank them for their six+ years of service to the internet community.
Perhaps a new service will appear to fill the void.