Hi there, thanks for your question. In order to begin answering it, we need more information. Can you please tell us details like: * Any error message that gets displayed * Your version of Thunderbird * Your operating system * Any recent changes to Thunderbird (an upgrade, add-ons being installed, etc) You may also want to try Troubleshoot Mode to see if that solves the problem: [[https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird]] Additionally, have you contacted your ISP (Charter/Spectrum) to see if they've made any changes to their email login requirements? Just thinking out loud here, but that's worth a shot.