Scriptable Notifications 6.0
by electrotype
Allows you to define an external script (bash, batch, python, ...) which is called so you can manage mail notifications / alerts the way you want.
Snap/Flatpak versions of Thunderbird not supported.
About this Add-on
Please note that this add-on will not work with a Snap/Flatpak version of Thunderbird. It seems those don't support Native Messaging, which is a protocole required by this add-on. If you know how to fix this, please let me know!