I suspect that, even though you removed the email account, you may still have an active Address Book or Calendar associated with that account. Check those and remove them, too, if found.

Another, less likely possibility is that one of your current active accounts is using the SMTP (outgoing) server for the deleted account. You can check that for each account at <account settings account outgoing server p></account>

Please let us know what you find.

Thank you for your assistance. I will lookalike that later when time allows. The deleted email account, and the current one i am using, are both Gmail accounts. I'm not sure how to delete outgoing server for the account that I have already removed from Thunderbird. And for sure without disrupting my current account. If I have an address book or calendar left hanging around, it is not visible, and I can't log in to that account to view and delete that.

Regarding the SMTP servers, the goal is to have a separate one for each Gmail account. They will all be set up the same except for the user name (email address.) So, check out the SMTP server for each Gmail account, and if you find one of them with the user name of the removed account, use the drop-down list to pick the one with the proper user name. If there isn't one...

Scroll down the list of accounts in <Account Settings> all way way to the bottom where you will find Outgoing Server (SMTP). Add a new one - it will be the same as the other Gmail accounts except for the user name. Now go back up to the account with the wrong user name and choose the correct one from the drop down list. You can now go back down to the bottom and Select and Remove the obsolete one.

If that was the problem, you're done! If not, check the Calendars and Address Books:

- Go to the Calendars tab and if you see a Google calendar listed that you down want, right-click on the name and choose "Unsubscribe Calendar".

- Go to the Address Book tab and if you see a Google Address Book you don't want, right-click on it and choose Remove. You might want to Export it to a Vcard (VCF) file first.

Ok. So, I did or tried to do all that you suggested. Except that the only other outgoing server was a default server. I deleted the other server, except for the default. I found an address book, and deleted that as well. Closed the program, re-opened it and the dialog box still opens, requesting my log in for the account that I no longer have. Every time Thunderbird checks for new messages, that box opens and I have to close it again. I am stumped, and considering uninstalling Thunderbird, and then reinstalling it again.. what would be your suggestion? I have 2 email accounts that I want to use in Thunderbird. Thank you for your help.

One last thing to try that might provide a clue: restart Thunderbird in Troubleshooting Mode. This will temporarily disable all add-ons, which could eliminate them as possible problems. To do that, go to <Help | Troubleshoot Mode...>. Let us know if your login prompt goes away.

Otherwise, I'll have to think about it some more, but uninstalling the program isn't likely to do anything. What WOULD be effective would be to create a new profile, You would have to set up your accounts and preferences again from scratch. If your two accounts are IMAP you wouldn't lose any messages, and you could import Local Folders, and other stuff, so the cost of the disruption to you would be just your time and patience. Should you decide to go this route, invoke Thunderbird's Profile Manager. To do that, quit Thunderbird, then (in Windows), press <Windows Key+R> to bring up the Run dialog box and type in "thunderbird -profilemanager" or "thunderbird -p" (no quotes), choose "Create Profile..." and you will be prompted through the process as if it were a new installation.

The mystery to me is that, as far as I can think of, the only things that would trigger Thunderbird to try to log into an online account are email, calendars, and address books. We seem to have eliminated those possibilities, though I still feel like I'm missing something obvious.

Maybe somebody else here has some ideas.

Well, I tried the troubleshoot mode. It asked for that password as soon as it restarted. I went into settings and changed the default of checking for emails upon start up, thinking this would at least keep it from asking for a password at startup and every 10 minutes to check for new email. Same thing. It still keeps asking for a password to log into that old account. I'm not savey enough to go into windows and change to a new profile. Something seems to remember that old account, even though I deleted it. Nothing seems to be showing up in calendar, or email, or address books. I even went into the saved passwords and removed all saved passwords, hoping a remnant was triggering that. No different. So, I guess I'll just keep closing that dialog box every so often, until I get the time and nerve to install a fresh copy of Thunderbird. Thanks for all of your help and suggestions.

Re-installing Thunderbird is unlikely to help. Anything that would be triggering a logon prompt would be found within your Profile. A brand-new profile would have no knowledge of any previous accounts and so would not ask for credentials.

Here is an article with better detail about what Profiles are and how to create new ones:

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles

Lin, Thanks so much for the assistance in fixing the problem. The link helped a bunch, since I was hesitant to go into windows programming to make changes. It was so easy even I could to it. Now I'm in the process of saving all of the email messages that I had saved into "Local folders" . It is time consuming, but has solved the issue of the unwanted email account login page. Thanks again, Gary

Glad to hear it! I'm still very curious about what was the real source of the problem, but sometimes it's better to stop spinning your wheels and move on..

I hear ya. There were 3 profiles counting the new one that I added. one was "default", this one was empty one was "default-release", the one that I was using, and the one that was the problem Thanks again