Author of Kill the Newsletter! here. Thank you for your comment. I tried the tool you mentioned before creating Kill the Newsletter! Of course, I was trying same work :)

Unfortunately, I ruled it out for two reasons. First, it required a Google account, thus binding my identity with my reading preferences. Second, I set up a throwaway Google account just to test the service and it didn’t work. I can’t remember exactly why, though.

It was definetly an inspiration for Kill the Newsletter! It gave me an indication that the project was feasible.