Gmail advertises QUOTA as an CAPABILITY upon connection before login. Dovecot advertises QUOTA as an CAPABILITY only after login. GPT believes this is why Tbird doesn't show the quota on the status bar, because it's looking for the quota before login and not after.
Does anyone know if its possible to get dovecot to advertise QUOTA before login?
Never mind about that, trying to put QUOTA before login. That isn't the problem, i found it.
It's a config issue with Tbird, by default it wont show the quota on the status bar until it reaches over 75% full. In the config window you can change this to 0% to make it always visible.
In Tbird settings, general tab, scroll to the bottom and open [Config Editor] Put "mail.quota.mainwindow_threshold.show" in the search and change the value from 75 to 0 (or whatever).