@aral @Dashtop How email apps should work today: You enter your email address & password. Only if it can't retrieve the other settings from the service (like Fastmail, there's a standard for this now) or a builtin database, then ask the user for them!
There! A cleaner, less-geeky UX that doesn't advertise email services which don't need more advertising!
Though even sticking to the current UX I don't see a valid excuse for dropping your pull request...
Though it strikes me that GTK headerbars should be more open towards window managers which want serverside decorations... Doing so shouldn't be hard, that codepath adding the window controls is already conditional!
And I'll agree of top-of-thread: Yuck!
For people who care about, support, or build Free, Libre, and Open Source Software (FLOSS).