Following on from the archived question "How do I reinstate notification of number of new emails in my taskbar icon" at https://support.mozilla.org/mk/questions/1395000 . This question is solved and archived, but I had trouble understanding the solution and I think others may also, so I have found another solution to add the new emails (red numbers) to the Thunderbird tray icon on Windows. Tools>Options>Add-ons Manager> (search) '''Windows Taskbar Unread Badge''' (--Put an unread mail count badge on the Thunderbird icon in the Windows taskbar--) > Add to Thunderbird.