I cannot find any information that explains how to use this add-on to sign into websites such as Quora, even though I learned about this extension when I went to sign into Quora while using the Multi-Account Containers add-on. The latter helps prevent Facebook (among others) from following you around on the web. There is a prompt on Quora's login page to use FF Relay to login, but Quora will not accept the alt email. I have repeatedly searched for info on how to login using these credentials, but can find zip about it.

IN REPLY to Developer Response: If you note in my original review, I said that Quora would not accept the alt address. I am not sure why it worked for you but not for me. I don't have that many add-on's other than adblockers and Privacy Badger and the two Container apps.