Rated 1 out of 5 stars

There does not seem to be a way to add new a new address to the drop-down. I just get my usual address. Not much new with that.

This review is for a previous version of the add-on (3.2). 

Identity Chooser simply shows all addresses that you've setup in Thunderbird.

If you add a new account (or a new address to an existing account), Identity Chooser will pick it up automatically.