Hello there Dvd '''''Cause''''' Greyed-out areas, folders, or menu options in Thunderbird are often caused by UI glitches, add-on conflicts, or synchronization issues. Areas are mostly frozen, greyed-out, or unusable. The symptoms can vary from minor to severe Are you using chrome as browser? Restarting in troubleshooting mode can help detect broken extensions or outdated add-ons that are cluttering our software. First, repair the view layout. Once that is complete, you can switch to classic view. '''''Restarting in troubleshoot mode''''' https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird. '''''To use ''''' Restoring classic view. '''''Open settings''''' : click the hamburger menu>on the top-right tittle bar and select settings. '''''Appearance tab''''' :click on the appearance tab in the left side pane. ''Message list classic'' : in the right-side pane.find the message list section. '''''Change view style''''' : change the ''view style'' to table view. '''''Enable classic view layout''''' : click the hamburger menu again. Select>view>layout>classic view . '''''Tip''''' Use a the latest version from us , thunderbird. https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird