(In reply to Vadim Krevs from comment #10) > I don't know enough about the details of what is going on - IMHO it would be > much better if you commented on in the upstream bugzilla yourself. I know as much as you about thunderbird internals :-/ The issue is that it calls nsMIMEInfoUnix::GetHasDefaultHandler way to often with totally nonsensical parameters, like "subsystem", "c", "C", "Zc".