I have the latest version available for download on the thunderbird site as of this date. I am unable to get a Gmail account working. It goes to a localhost address at the very end of the process, I think to pass the token back to Thunderbird from Google. It says it is blocked because it is unsafe. I already have a server running on localhost this appears to interfere with this setup process. I think maybe it would be better for thunderbird not to assume you have complete control over localhost and no other servers are running.