I want to use Vivaldi's Mail (I loved Opera Mail), but I prefer to use Firefox for browsing rather than yet another Blink engine. Unfortunately, Vivaldi Mail d

I want to use Vivaldi's Mail (I loved Opera Mail), but I prefer to use Firefox for browsing rather than yet another Blink engine. Unfortunately, Vivaldi Mail does not respect the default browser setting, and opens links from emails in Vivaldi only. This creates a mess of duplicate website tabs, logging in again, etc.