Abstract: If you cannot use you Gmail account via Thunderbird, you need to enable less secure device like mobile broadban connection via Gmail’s security settings, which are found from the link on the rejected connection.
1. If you are making the TB settings, bypass Gandi.net account
2. Put your Gmail address and password
3. If you get the error message, login via browser and open “the rejected connection post”
4. Open the link for settings
5. You will see the quoestion about your (unknown)device and location. Click “Yes check the settings”
6. Enable less secure apps (Gmail thinks that mobile broadband is less secure?).
7. Now Gmail works with Thunderbird