The words 'Primary Password' have a specific meaning. This setting is not set up by default. It is a setting enabled by you. The purpose of the 'Primary Password' is to stop all those people to whom you allow access to your computer and and your user account from being to see all your mail account passwords stored in Thunderbird. In Thunderbird Settings > Privacy & Security' Scroll down to 'Passwords' section. If you set it up then this checkbox will be selected 'Use a Primary Password'. This 'Primary Password' has nothing to do with mail accounts. It was set up by you as a separate level of protection. You would not have used your mail account password for very obvious reasons. If you cannot remember that 'Primary Password' then you have only one option...to remove it completely. AS it was set up to offer protection to keep mail account passwords secure, when you remove the primary password, it will auto delete all stored passwords. After all any one with access to your computer could remove it, but to maintain security, all passwords are removed. So you will then get asked to enter normal passwords. Follow the instructions at this link to remove the Primary Password. I've also added an image below which you can use as a guide * https://support.mozilla.org/en-US/kb/protect-your-thunderbird-passwords-primary-password#w_reset-your-primary-password-if-you-have-forgotten-it Then restart Thunderbird. Enter the correct mail account passwords when prompted. Remember to select the checkbox 'Remember Password' before you click on OK.