Hi Leonard,

just a quick heads-up,

using  the version of thunderbird you've mentioned, and jaws 2020 august
release, when you go to account settings,

tab until you hear "account settings document," for a second time; at
this point, arrow down once, and you should listen jaws announcing the
tree view, so push bar space, and now you can actually interact  with
the tree view using up / down arrows.

hth

Leo

“Pain is inevitable. Suffering is optional.”
― haruki murakami,