Reinstalling has no impact on your profile data.

Windows does NOT shut off access to email. So the two most likely causes of your problem are a) antivirus software is blocking accesses (what AV software are you running?) or b) somewhere along the line a new Thunderbird data profile got created (which gives the appearance that you lost your data/accounts) - profiles are listed by using the profile manager https://support.mozilla.org/en-US/kb/using-multiple-profiles

your older emails, accounts, settings, etc should be inside older TB-profile.

a TB-profile is located here: • in windows: "%APPDATA%\Thunderbird\Profiles\<profile-name>\" that is usually: "C:\Users\<WindowsUserName>\AppData\Roaming\Thunderbird\Profiles\<profile-name>\" • in Linux/Unix: "~/.thunderbird/<profile-name>/" or "~/.mozilla-thunderbird-<profile-name>/" that is usually inside main/default volume: "/Users/<Linux-Unix-UserName>/.thunderbird/<profile-name>/" or "/Users/<Linux-Unix-UserName>/.mozilla-thunderbird-<profile-name>/" • in macOS: "~/.thunderbird/Profiles/" that is usually inside default volume: "/Users/<macOS-UserName>/.thunderbird/Profiles/"

TB = Thunderbird.

inside the current TB goto main menu > Help > Troubleshooting information > about:profiles > Root directory. find the line "Default profile: yes", in that section , in the "Root" directory line, the last sub-folder is your TB's TB-profile folder. if open folder/location button exist, use that to open the location in windows explorer File browser. remember that last sub-folder's name , lets call it "TB-new-profile-name" folder.

go backward one folder in windows explorer File browser, you will see similar more sub-folders , other folders which are not TB-new-profile , one of those sub-folder is your "TB-old-profile-name" folder.

if your TB in your Windows is installed here: "C:\Program Files\Thunderbird\" and, if your "TB-old-profile-name" folder is here: "%APPDATA%\Thunderbird\Profiles\TB-old-profile-name\"

then start "Command Prompt" window, and start TB with a different profile, in this way: "C:\Program Files\Thunderbird\thunderbird.exe" -p "%APPDATA%\Thunderbird\Profiles\TB-old-profile-name\"

if above old TB-profile folder is not correct old-TB-profile , then exit from TB , and use above command again but this time use a different old profile sub-folder name , as shown under "Profiles" sub-folder.

if above old folder is correct or when you found correct old-profile , then exit from TB, and to use that correct old profile permanently, use such command: "C:\Program Files\Thunderbird\thunderbird.exe" -ProfileManager or try this: "C:\Program Files\Thunderbird\thunderbird.exe" -P a profile choosing/selection window will appear: https://www-archive.mozilla.org/support/thunderbird/profile select the old profile name , & select "Use this profile permanently" option or similar option. only "profile-name" portion will be shown inside profile selection window , not the "xxxxxxxx" portion of full profile-name folder: "xxxxxxxx.profile-name"

then double-click on TB icon will start the TB with the old profile.

if you want to, or users who want to, can keep thunderbird auto-update disabled https://stackoverflow.com/a/64980413/3553808 . (please upvote my Q+A both, inside the linked page, if its useful/helpful).

Thank you for reading and responding to my plea for help. When I wrote that I deleted/reinstalled Thunderbird, I should have added "entirely" I remove all the profiles, all data, all Mozilla and Thunderbird folders. I have no antivirus running and I did get one of a dozen accounts to stick "on." Any ideas? I am already moving to eM Client's Pro version (30+30 day free trial). I would prefer to stay with Thunderbird, but charity support seems insufficient.

The topic now has an accurate summary.

The rest is awfully fuzzy without full information - ISP? , OS, gmail and type of auth settings, (no AV??). But it's perhaps mostly irrelevant, given that one of our gmail accounts works flawlessly. But sounds like gmail configuration.

The ISP is AT&T and a dozen other devices are using it flawlessly, including access to the same dozen gmail accounts. The OS Win10 was updated, as I mentioned, and that caused the problem. I am using the same auth settings trying to add to thunderbird 2.gmail.com as are functioning on thunderbird for 1.gmail.com and et cetera for all the other accounts whose passwords were not changed by Win10 and are working on my iPhone and mac computers. Some sort of tecchie nit arose overnight with the automatic/forced Win10 "update."

Thanks again for your interest.

AFTER COMPLETE DELETION OF ALL MOZILLA AND THUNDERBIRD FOLDERS ALL PROFILES AND DATA DELETED. WIN 10 RE BOOTED. COMPLETE NEW DOWNLOAD AND CLEAN REINSTALL OF THUNDERBIRD. WINDOWS DEFENDER TURNED OFF. NO ANTIVIRUS.

Screenshots attached to document defective Thunderbird Account Setting pages.

Please suggest a remedy or warn others to avoid this product/version.

Thanks further.

The situation is unchanged. NO SOLUTION. ONE ACCOUNT LIMIT ON THUNDERBIRD

Volunteers suggested using "OAth2" authentication, which is:

(1) No longer an option to select when adding an account (SEE SCREEN SHOTS OF NEW ACCOUNT PAGE)

(2) Not needed as "Normal Password" authentication works in the one account (of 12 gmail accounts having identical structure) that I was able to restore after Thunderbird was rendered incompatible by the latest Win10 automatic/forced "update"

NOTED ON OTHER CHAT/SUPPORT PAGES: PERSONAL ABUSE FROM UNHELPFUL MODERATOR IN RELATED POSTS. THIS "SUPPORT" SEEMS TO BE SOME SORT OF SHILL FOR MOZILLA. REMARKABLE AND SHAMEFUL DETERIORATION OF THUNDERBIRD AFTER 20 YEARS OF RELATIVE STABILITY. >>>>>>>>>> www.getmailbird.com/the-best-mozilla-thunderbird-alternatives-for-windows/

THIS IS A TEST.

MY UPDATE WITH ADDITIONAL INFORMATION DID NOT APPEAR

I INCLUDED REFERENCE TO PERSONAL ATTACKS APPEARING ON THESE "SUPPORT" PAGES BY A MODERATOR UNABLE/UNWILLING TO HELP WITH THIS TECHNICAL ISSUE.

IF THIS DOES NOT APPEAR, THEN I WILL GET TO OTHER IP ADDRESS AND OPEN NEW ACCOUNTS TO SHAME THE CENSORS AT THIS SITE AND WARN OTHERS THAT THERE WILL BE PETULANT VOLUNTEER SUPPPORT, IF ANY, AS NEW PROBLEMS ARISE WITH THIS UNSUPPORTED PRODUCT.

AS YOU CAN TELL, AFTER 20 YEARS OF LOYALTY I FEEL BETRAYED AND I AM JUST ABOUT DONE WAITING FOR ADULT SUPPORT AND DECENCY. ALTERNATIVE TO THUNDERBIRD ARE A CLICK AWAY

OK. That appeared. I will check again in the morning. Took a screenshot to document any delayed censorship

There is no censorship. All replies that include a link or text that resemble a link or spam is automatically held for moderation.

if you want to, or users who want to, can keep thunderbird auto-update disabled https://stackoverflow.com/a/64980413/3553808 . (please upvote my Q+A both, inside the linked page, if its useful/helpful).

totally irrelevant

Hi The first image you attached provides good information. It shows the server name for imap as .gmail.com You need to edit that so it says imap.gmail.com

set port: 993 Set Connection Security: SSL/TLS Set Authentication Method: OAuth2

The smtp server name says: .gmail.com It should say: smtp.gmail.com set port: 465 Set Connection Security: SSL/TLS Set Authentication Method: OAuth2

Thanks for the screen shots. I quite agree with Matt's excellent advice in https://support.mozilla.org/en-US/questions/1324611#answer-1389667

The screen shots contain "unable to connect to our sign-up server" and "failed to find the settings for your email account".

The wording of these doesn't make the cause obvious, but after researching and testing myself with network disabled on my computer I can reproduce both items. So it is 100% clear something is blocking network access to your mail provider and also to the website used to "autoconfig" accounts.

This could be caused firewall, proxy, router ... and other possibilities both hardware and software. One possible starting point is restart Windows in safe mode, and then also start Thunderbird in safe mode, which will ensure no third party software is running when you start Thunderbird.

Hi The first image you attached provides good information. It shows the server name for imap as .gmail.com You need to edit that so it says imap.gmail.com ...

This would normally be great advice, but in this case the user's networking is hosed. This is what causes a ridiculous value of ".gmail.com" in the server field.

Until the networking issue is resolved there is no hope of progress.

Hi Todd, you have indeed noticed the first step in the problem. I did that first. It does not work on 11 of my 12 accounts. By putting in the correct parameters repeatedly I somehow got one account to work. I copied exactly the entries for that account on 11 other accounts and every single one failed. Usually I get a yellow bar error message across the account profile page. Once in a while I get past that and it asks for the account password. But I enter the password and it is rejected as incorrect. I have done this 11 times with 11 different accounts with 11 different passwords and repeated some of them multiple times after verifying the passwords are correct. I have been using Thunderbird and solving problems not as bad as this for 20 years. This is the worst I have ever seen which is why I am so upset and preparing to leave Thunderbird. If you can shed any more light on this please let me know. Thanks again for your interest

I do like the safe mode idea and I will try that next.

The complete instructions...

Start *Windows'* safe mode with networking enabled - win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

Still In Windows safe mode, start thunderbird in safe mode - https://support.mozilla.org/kb/safe-mode-thunderbird

And I forgot to mention, that whatever is going on with networking might be intermittent - now you see it, and now you don't.