Thunderbird authentication error

If you use Mozilla Thunderbird, you might sometimes see the issue when adding a new account:

Unable to log in at server. Probably wrong configuration, username or password.

There could be different reasons for that, but we will list here the most common reasons:

Gmail

If you use gmail, and use 2-FA (two-step) authentication, then you will need to enter (instead of your gmail password) your APP PASSWORD. Go to https://myaccount.google.com/apppasswords and generate it and enter it in PASSWORD field, when adding an account; and choose “AUTODETECT” instead of OAuth2. 

Click DONE. That’s all ! 

Hope it helped.