The email address should be entered automatically in the Sign In window, and when it isn't, it's usually because cookies aren't accepted in TB Settings/Privacy & Security. That's necessary for OAuth2 authentication, which you should have for the authentication method for incoming and outgoing in Account Settings.

Remove the entries for the account from Saved Passwords in Privacy & Security, accept cookies, restart TB, enter the new account password in the OAuth window to allow TB access. If all goes well, there should be an oauth:// token for the account in Saved Passwords.

Hello there

The error code 403 makes it clear that the server understands your request, but refuses to authenticate it.

Also re-authentication will not work because access belongs to the data application. just like 1 goes with 2 and 3.

Greetings Firefox volunteer.

Sfhowes, I tried your approach. It did not work. Every time I try to send a message in T-bird, and even when I just open the program, I get a prompt to go to Google for a password, and this leads to an error message. Even after I followed your instructions. There is no way to get rid of the 403 error screen without shutting down T-bird.

All my server settings are what is recommended by my institution and what I have been using for years. I notice one change: the incoming server option is only SSL/TLS, not SSL.

I attach images of what I'm getting when I open the program.

Confirm the following:

cookies are accepted in TB (not your browser)

there are no entries for the account in Saved Passwords

the settings are imap.gmail.com, 993, SSL/TLS, OAuth2 authentication, User Name = yourNetID@nyu.edu smtp.gmail.com, 465, SSL/TLS, OAuth2 authentication, User Name = yourNetID@nyu.edu

after restarting TB, the Outh window appears and you enter your Google Apps password

These are suggested here

state your antivirus and VPN, if applicable.

I followed all instructions above and still come up with a "403" error message when I try to enter my Google password.

I have also consulted with IT at my university. Their fixes were the same as yours, but nothing works. I have spent an enormous amount of time on this. I never had trouble with earlier versions of T-bird. The update has been a disaster for me, and now I can't even use the program.

So, unfortunately, I think I must just put up with G-mail and say goodbye to Thunderbird.

I am also getting the 403 error when I updated my password as required by my university. The update worked in previous years so I am pretty sure it is a Mozilla Thunderbird problem