Review for Windows Taskbar Unread Badge by nami75
Rated 3 out of 5 stars
The badge doesn't appear neither on the envelope icon in the tray nor on the Thunderbird icon in the active programs part of the taskbar.
Windows10 1809, Thunderbird 60.4.0, Windows Taskbar Unread Badge Version 1.2.20181207
Edit
Disabling Windows 10 "use small taskbar buttons" settings
now the badge appears,
however when have 1 unread message it shows 6, reading this message it shows no badge.
Using POP accounts
To create your own collections, you must have a Mozilla Add-ons account.