Downloaded gnome-open addon manually (as it is not found when searching for addons from within Thunderbird) and that solves the issue also for me (just note that because in earlier post (comment #4) of spadger it was not clear for me which of the two mentioned addons solved the problem.
Downloaded gnome-open addon manually (as it is not found when searching for addons from within Thunderbird) and that solves the issue also for me (just note that because in earlier post (comment #4) of spadger it was not clear for me which of the two mentioned addons solved the problem.