''re: Started after trying to re-establish gmail on mobile phone'' Did you have to set up a two part verification to see gmail emails on the phone? This is gmail trying to set up a more secure system for those who use phones to access emails etc. * http://kb.mozillazine.org/Gmail '''Two step verification''' ''The Google Account help advocates using two step authentication. That sends a code (a minimum of once a month but ideally every time you log in) to your cell phone that you need to enter when logging in using a browser. '' ''However applications such as email clients can't do that. If you configure two step verification you need to create an 'application specific password' for Thunderbird that you use instead of the normal password. The application specific password doesn't change when a new code is sent to your cell phone.'' ''Two step verification is not needed, and not recommended. Use a strong password, and don't use the same password with other email providers/web sites, instead. However, if you have another email account it is a good idea to set a recovery email address in case you ever forget/lose your password. '' So although it is not absolutely required, if you have set up a 2step verification, then you will need to use your application specific password in your gmail account in Thunderbird to access IMAP. Info on application specific password: * https://support.google.com/accounts/answer/185833?hl=en&topic=1056283&ctx=topic Remove old stored password, restart Thunderbird and enter the 'application specific password' at the prompt. '''How to remove old stored password:''' * Tools > Options > Security > passworda tab * click on 'Saved passwords' * click on 'Show passwords' * Select both mailbox and smtp mail account passwords. * click on 'Remove' * click on 'Close' * Click on 'OK' Close thunderbird and wait a few moments for background processes to complete. Then restart Thunderbird.