Access the account on the gmail website, delete the Spam and Trash folders, then delete messages that arrived around the 14th when they stopped downloading to TB. The aim is to delete the corrupted message that is blocking the download of the newer messages.

https://support.mozilla.org/en-US/questions/1279488

Once you get this fixed, keep in mind that you can't download POP mail on multiple computers unless you enable 'recent mode' in gmail. IMAP is usually a better choice when an account is read from multiple devices.

"Once you get this fixed, keep in mind that you can't download POP mail on multiple computers unless you enable 'recent mode' in gmail. "

I did have recent mode activated on netbook. In Email address I had recent:xxxxxx@gmail.com and it worked well for several years. Then suddenly Tbird started interpreting this as actual Email address and giving error. So I eliminated the "recent:" and started having the problem I've described.

So I guess the question is – why did Tbird suddenly start misinterpreting recent:xxxxxx@gmail.com?

Can't say whether TB has changed how it handles recent mode or if Google has changed it. Their only advice is to remove the account and add it again. If you have TB 68.5, gmail POP accounts can use OAuth2 authentication.

sfhowes said

Can't say whether TB has changed how it handles recent mode or if Google has changed it. Their only advice is to remove the account and add it again. If you have TB 68.5, gmail POP accounts can use OAuth2 authentication.

Both netbook & new PC have v. 68.5.0. What would OAuth2 authentication do for me? How to I specify it in account settings?

Also, wouldn't removing a pre-existing account destroy all folders and Enail history?

Thanks — Lyndon

OAuth2 is under authentication method for the incoming and outgoing servers. It works independent of the 'less-secure apps' setting in gmail, app passwords and two-step-verification, so it makes it simpler to add the account to TB.

Before you remove an account, copy the mail to subfolders of Local Folders.

sfhowes said

Can't say whether TB has changed how it handles recent mode or if Google has changed it. Their only advice is to remove the account and add it again. If you have TB 68.5, gmail POP accounts can use OAuth2 authentication.

Currently I have set up just a single Tbird account, my main account. Local Folders has been set to store contents in a folder Local on an external portable HDD. Inbox contents have been stored there also in a file Inbox Keep.

I need to remake the main account. This seems to mean deleting the current one and creating a new version of it with basically the same settings. Can the Tbird client exist temporarily with just the Local Folders account, until I create the new version of the main account?

To first delete the main account, it looks like I go into Account Settings, then Account Actions, and select Remove Account. Correct?

Then to create (i.e., remake) the main account, I would go into Account Settings, Account Actions, and select Add Mail Account. Correct?

Is this the correct procedure for remaking the account?

Thanks — Lyndon

That's correct for remaking an account, but if you're not switching between POP and IMAP, just change the settings, then delete the passwords from Tools/Options/Security/Passwords/Saved Passwords, restart TB, and enter the password when prompted. With OAuth2 authentication, the regular account password is entered in the OAuth browser window (cookies must be enabled in TB Tools/Privacy).