That might be it, Thunderbird works really well with auto configuration of domains that it doesn’t know but has DNS entries.

How would you even know what ties a person has when the problem is government level security. Besides, Russia doesn’t exactly work on government payrolls anyway, it’s more about working in subsidiary companies owned by the oligarchs who are able to skirt the law effectively becoming the government in the process. It’s totally foreign to Western style government, there is nothing like it in the world