this I DDG'd with the words "lost password account thunderbird linux" and read through scanned quickly dozens of posts.
Many solutions but I remember this could be a starting place (https://support.mozilla.org/en-US/questions/1293814)"
"Check to see if a password is stored in Thunderbird:
Menu app icon > Options > Security > 'Passwords' tab
click on 'Saved Passwords' button
click on 'Show Passwords' button.
Each account will have:
either a line starting with 'mailbox://....' line if you have a pop mail account,
or a line starting with 'imap://....' line if imap account
and a line starting with 'smtp://....' line for the outgoing smtp.
If you use Oauth for authentication method then you would see a line starting with 'oauth://....'
Can you see the lines for you mail account? If no, then they are not stored in thunderbird. This file may have been effected with loss of data when computer crashed.
All mail accounts will have a password. When Thunderbird needs to access the server, the server has to authenticate that it is the correct account, so it requires a username and a password. The username is usually the full email address.
Passwords are created or modifed or reset in the webmail account which you access via a browser. They are not created in Thunderbird. If you cannot remember the password, then there will be a 'forgotten password' link where you try to logon to webmail account.
If the email address is supplied by your Internet Service Provider, then you will need to follow the instructions at the 'Forgotten Password' link.
If you set up an email address using a free service like gmail, then they will usually send an email to another of your email addresses or a text message to a phone number which you previously gave them for such purposes. That email or text mesasge will have a code which you use to gain access to the account. Then you can reset the password.
Once a new password has been set up in the webmail account, logout of webmail and then test new password by logging in again to webmail account. "
**I feel like I am missing an important detail. You are saying "create new account" in Thunderbird does not create a new account: it disappears the old account and deletes it then replaces it? Doesn't seem like app behavior especially if it doesn't explicitly tell you it's doing that. but I don't use an aggregate so I have no experience here exactly.
I wonder if Solus through keys/auth mechanisms stores app passwords too? I agree with you. It exists somewhere. I don't know where. maybe in the articles. you have to start somewhere.
