There are two parts to Thunderbird. 1. The application. Because it is cross platform it actually interaces with the operating system only enough to perform integrated function like being a default mail client. Very little is stored in say the windows registry. 2. The profile. This is your settings, user data and mail. This is all stored in the profile and it the part that is generally moved from machine to machine when you buy a dew device so you don't have to start all over again. Removing the application does not change this part at all. Unless you use some third part uninstaller. Then what you get will depend on your choice of uninstaller. So to answer your question if you uninstall Thunderbird and reinstall the same or later version, it will just pick up your old profile, or it should by design. Based on the last part of your post, I assume you are trying to fix some issue. Reinstalling rarely if ever fixes anything other than operating system integration issues. It can be a trigger for antivirus programs to actually get out of the way and let the application function, and it can replace corrupt components. It is most unlikely to fix the issues shown here https://support.mozilla.org/en-US/questions/1430332 and it most certainly will not fix the issues discussed here. https://support.mozilla.org/en-US/questions/1425510 Essentially ATT email is a special brand of rubbish that has to be undertaken exactly as they tell you or simply bypassed as a waste of time. I prefer to simply abandon ATT and use Yahoo directly for ATT customers, but for those with technical issue is is more difficult. It appears to me that you abandoned your discussion with SFHowes where you were being instructed on what had to occur for ATT to function in the crippled manner they have negotiated with Yahoo. Essentially I think Steve is correct, your issue is the ATT mail key there and perhaps here as well. Incoming and outgoing servers has separate passwords. You possibly have more than one outgoing server configured as well. But in none of your posted images is there anything about your outgoing server (SMTP) entries. They are in account settings, but listed under the outgoing heading not the incoming account settings. There should be one outgoing server configured for each incoming one. Fundamentally there are three main causes of email failure with ATT 1. The user fails to use the mailkey is all instances, for some reason having two saved passwords for two mail server appears to escape many. 2. The user has an antivirus product installed that is something of a problem. This especially affect folk that have limited technical skills as they tend to be more paranoid about what can happen. They are also more susceptible to the fear selling that antivirus vendors thrive on. These folk tend increase "security levels" in their chosen security /antivirus package to improve their security and in the process basically disable anything but the web. The standard diagnostic for that is to run your operating system in safe mode with networking. So we come to this question. Does Thunderbird work as expected with your OS started in '''[http://en.wikipedia.org/wiki/Safe_mode safe mode with Networking]'''. Instructions for each operating system: [https://support.microsoft.com/en-us/windows/start-your-pc-in-safe-mode-in-windows-92c27cff-db89-8644-1ce4-b3e5e56fe234 Windows 10/11], [https://support.microsoft.com/en-us/windows/windows-startup-settings-including-safe-mode-7f31dcea-6427-0ba0-ec1b-729a56321cd3 Windows 8], [https://support.microsoft.com/en-us/windows/advanced-startup-options-including-safe-mode-b90e7808-80b5-a291-d4b8-1a1af602b617#start-computer-safe-mode=windows-7 Windows 7], [http://support.apple.com/kb/ht1564 OSX] 3. The mail setting are all messed up because previous attempts to fix things have not works and not been reversed. So we get to this request. * Open the menu '''[[Image:Fx57Menu]] > Help > Troubleshooting Information''', then click '''Copy text to Clipboard'''. * Go to https://pastebin.mozilla.org/, paste the clipboard by right clicking in the large text area, select paste from the menu, change the retention period to expire in 28 days (or as long as it will allow), use the '''Paste Snippet''' button to create a page containing your info, then copy the resulting URL (address) of the page created. * Open a reply to this post, and paste the URL to your troubleshooting information you just copied.

This is what I got... Could it be the printer settings? https://prod.pastebin.prod.webservices.mozgcp.net/wTtuRCg3

I got it fixed using these settings. https://support.mozilla.org/en-US/kb/thunderbird-and-yahoo Thank you to all that helped me with this issue I had. :)