Just a passing comment: I have never had success with gmail when inserting the password when setting up the account. You might try starting over and omitting password.

Thanks. I tried that, but it did not work. At step 7 in my original post, this time I did not enter the gmail password. And I tried both ways, with "remember password" checked or not checked. However, the remaining steps, including the final error message, were exactly the same. *** A1) I am going to try the TB manual config some, as that will at least let me separate imap from smtp. Maybe I can at least make imap work, and then move on to smtp. *** A2) Do I need to set up a google app password for this to work? I previously thought it was required and have one set up. It would help a lot for me to know for sure if google app password is or is NOT needed. Thanks

My experience has been to use no password and on first clicking to download messages, I receive a google login prompt that applies the password for me into thunderbird.

I do receive a google login prompt. However, I get the TB “Unable to log in at server. Probably wrong configuration, username, or password” error message, as previously stated. I cannot further troubleshoot this for a few days, as I'm occupied with other things. But I am going to get back to this. So please leave open. In the meantime, can someone please verify for sure, yes or no, whether I need to set up a google app password for this to work? Thanks

I'm closing this thread in a few days. I tried every variation I can imagine on my windows 7 desktop. For example, I turned off windows defender (not trivial to do). I turned off windows firewall (not trivial to do). I turned off / uninstalled malwarebytes. I tried many combinations of TB settings. I reviewed the gmail settings. Yet I was never able to connect TB to either gmail imap or gmail smtp. There was always an authentication failure.

In contrast, my windows 7 laptop TB easily connected to both gmail imap or gmail smtp, very easy to do. That connection will suffice for my purposes. Instead of using the gmail smtp server on the desktop, I found sendgrid smtp server which works well. I wish I had a backup smtp server, but I just have to hope that the sendgrid server continues to work. I can use the laptop gmail imap connection to help clean up files better than the clunky gmail interface.

I give up trying to make it work. It is just too frustrating trying to diagnose this problem, because I lack the diagnostic tools to tell me EXACTLY what is causing the authentication failure. It seems something to do with the desktop windows 7 configuration, since the windows 7 laptop works perfectly, and because countless other people easily connect. But just guessing and floundering like I am doing is a time waster. The lack of diagnostic detail makes this a frustrating problem for many, as I have seen many other posts with basically similar problem.

I appreciate the response I received, even though not helpful to solve the problem. Given the apparently irreproducible nature of the problem, seems something local with my windows 7 setup, the only response that would have helped would be to point me toward some TB or windows or gmail diagnostic tool that gives more detail why the authentication fails. I tried all the TB developer tools, such as error console, but not helpful at all. I could not find any gmail / google diagnostic logs relevant to help solve this authentication problem. Any diagnostic tool someone would suggest? Otherwise, will close thread in a few days. Thanks

I'm closing this thread in a few days. I tried every variation I can imagine on my windows 7 desktop... In contrast, my windows 7 laptop TB easily connected to both gmail imap or gmail smtp, very easy to do...

Different versions of TB on each computer? Desktop Auto-updated? I have a Windows 7 machine that is very stable, but I need to run VM on any updates to make sure it doesn't hose anything up since Win 7 is no longer supported. I ask because I believe I'm still on 107.XX on Windows 7 computer.

Same version of TB on laptop (connects to gmail) and desktop (authentication failure). TB 102.8.0 was installed to both at the same time, and not updated since. Both laptop and desktop say Windows Home Premium Service Pack 1. Again, I believe there is something local on the desktop computer. I have tried disabling just about everything and the connection still fails. Unless there is some better diagnostic tool, I'm giving up.

I would like to close the thread, with problem not solved. Thanks

re :Do I need to set up a google app password for this to work? I previously thought it was required and have one set up.

If you have set up 2 step authentication in gmail then when you try to create the mail account gmail will expect that google app password and not the normal password you use to access webmail. This probably explains why you are getting the pop up that says " “Unable to log in at server. Probably wrong configuration, username, or password”. "

If you disable that 2 step verification then you can just enter the normal password when creating the account and when verifying in the gmail popup to allow Thunderbird.

Thanks for responding. I didn't explicitly say so, but I did "try every variation", including your good suggestion, and it did not work. Originally, I was using 2 step authentication. On Windows 7 desktop, would not authenticate when A) trying to send an email from TB using gmail smtp server, and B) trying to have TB read gmail imap server, as previously explained. Later, I got tired of the repeated 2 step authentication and so disabled it. The results were the same: A) and B would not authenticate on desktop. Later, I tested from a TB install (same TB version) on a windows 7 laptop (same OS version). Authenticated perfectly and easily. Again, I believe there is something local on the desktop computer. Everything in TB and gmail is the same between desktop and laptop, but desktop fails to authenticate. Unless there is some better diagnostic tool, I'm giving up. It is too inefficient guessing. Thanks