The specific problem is "Normal Password" does not work unless you use a mailkey password issues by ATT, but nothing works if your anti virus/ Firewall are on the blink. Hence the following standard advice to test if it is so. The first generally disables the forced inserting of anti virus components into Thunderbird, a common point of failure post update. The second generally disables the anti virus and it's application firewall.

The specific problem is "Normal Password" does not work unless you use a mailkey password issues by ATT, but nothing works if your anti virus/ Firewall are on the blink. Hence the following standard advice to test if it is so. The first generally disables the forced inserting of anti virus components into Thunderbird, a common point of failure post update. The second generally disables the anti virus and it's application firewall. *Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender. *Restart the operating system in '''[ safe mode with Networking]'''. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: [https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode Windows 10], [ Windows 8], [#start-computer-safe-mode=windows-7 Windows 7], [#start-computer-safe-mode=windows-vista Windows Vista], [?mfr=true" Windows XP], [ OSX] ; If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.