I've had Thunderbird mail for some years but I haven't been using this computer for about 18 months. (Mac High Sierra). MacBook Pro 17-inch mid 2010 2.66 Ghz Intel core i7. 8 gb memory I came to open Thunderbird mail today. It was all set up as before. The Yahoo accounts were fine, and Cloud. But when I opened Google it gave me: "Authorization Error. Error 400: invalid_request You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy for keeping apps secure. You can let the app developer know that this app doesn't comply with one or more Google validation rules." I went to Google and was able op open google mail fine as a standalone M-Gmail (https://mail.google.com/mail/u/0/#inbox) How can I incorporate gmail into Thunderbird.? Sincerely Charles Davey