Top menu bar: Tools: Options: General section Or Menu button (top right): Options: Options: General section You will see what I show in my screenshot below. Select the options for '''Show an alert''', '''Show a tray icon''', and/or '''Play a sound'''. If you still get nothing after setting these and restarting Thunderbird, then there is something wrong with your Thunderbird installation or your Thunderbird Profile. Thunderbird stores all personal data such as messages, address books, calendars and configuration settings in a hard drive folder called the Profile. This folder is separate from the installation of Thunderbird. When Thunderbird is uninstalled, it will leave behind your Thunderbird Profile folder, which will be found and used again when you install Thunderbird again. This means if the problem is with your Thunderbird Profile, not the program installation, then reinstalling Thunderbird will not help. Creating a new Thunderbird Profile will help. [https://mzl.la/2lBfidM Profiles - Where Thunderbird stores your messages and other user data]