I lately discovered the feature that I can block all the cookies and allow some websites by exception. This is great because it works just like any firewall. Block everything and allow whats necessary. Problems are: 1. Every time that I have to add an exception we have to navigate to about:preferences#privacy. There could be an easy button to add exceptions. 2. The exceptions are not being sync so every different browser that I'm logged in I have to add the exceptions again. Cheers.