That is funny because 128.2.1 was updated with some changes that essentially broke Microsoft and Gmail oauth in 128.2.2. Those changes were backed out of 128.2.3. The backout of the changes what all that the update contained AFAIK See https://www.thunderbird.net/en-US/thunderbird/128.2.3esr/releasenotes/

128.2.2 release notes https://www.thunderbird.net/en-US/thunderbird/128.2.2esr/releasenotes/

128.2.2 is working perfectly fine for all my accounts as we speak. As soon as I update to 128.2.3 one of my gmail imap accounts starts showing login errors. This is pretty strange because I have another gmail and a yahoo imap accounts which seem to work fine with 128.2.3. I've already updated to 128.2.3 and back twice, but I will try again.

> I updated to 128.2.3 and login to gmail imap fails.

VKU do you recall what was on the screen when it failed?

It was a pop-up at the lower right side of the screen that said imap login failed. Indeed I could not see mail being sent to that account even though on a different device the mail was received properly.

The only thing I can see so far was that the failing gmail account had my email id without @gmail.com in the TB server settings. Two other ids I have which are working in 128.2.3 have @gmail.com included.

I was in the process of changing my email id from xyz to xyz@gmail.com. As soon as I did that I got a message that all my filters that placed email in my spam folder were disabled. Once I fix all these up I will try again.

That was it! After I changed my User Name for the failing gmail account from xyz to zyz@gmail.com in Server Settings, everything is working in 128.2.3, both sending a receiving email. I had to authenticate/authorize for both actions after I installed the 128.2.3 and all's fine. Surprisingly, my smtp user name is still xyz. I did not have to change that to xyz@gmail.com.

Observation: in the past a simple user name without the @gmail.com ending used to work for imap.gmail.com. This is no longer the case starting with TB 128.2.3.