Rated 5 out of 5 stars
seems to work fine for me in TB3.0. when i double click on the image in the message header, the Contact Card for the sender opens in a dialog box.
I turned off the gravatar in the options, since I don't know anyone using gravatars (hadn't even heard of it before this add on), but it worked even before I did that anyway.
Fabulous little add-on as far as I can tell!