Noté 5 sur 5 étoiles

Still works on TB 52.9.1! Allows you to set delivery status notification to on, by default, and several other options. Exactly what I was looking for. Not sure why this option was removed from Thunderbird, but it should be included, so thanks to the developer of this.

Noté 1 sur 5 étoiles

It appears that the add-on is not actively deveoped past TB 49 and thus unfortunately obsolete