It's amazing that they are so uneducated about DMCA. This is called defective DMCA notice, and it should be ignored. The sender of the notice can now file a suit, since the publisher of the list is no longer under safe harbor. But they won't, since they know it is defective. And if they did, it would be thrown out with a summary judgment.
The notice does not list the copyrighted works that are being infringed (I.e. made publicly available). This is the necessary element of a valid DMCA notice.
In this interpretation, the list of the specific copyrighted protected works that they provided a circumventing technology to access, is absent from this notice. I believe no legal theory works here, and I can refer them to a capable law firm if they are interested.
> What copyrighted protected works did they provide circumventing technology to access?
Anything behind a paywall. I'm not defending what they did. But I sort of understand how it could be permissible under the DMCA. (A law regarding which the EFF and I share many opinions.)
Apparently the copyright of web pages behind a pay wall. Blocking the ___domain causes their pay wall to not work - they probably load pay wall scripts from there - and allows unauthorized users to view their client's page without compensating them.
It's similar to having a movie theater with a locked door. We want to see the movie, but we don't want to pay, and distributing lock picking tools is illegal. And their door is "designed to only stay locked when a light is shining on it".
Here again, we are using technology to disrupt old laws.
