Re: What's wrong with the built-in mail client on WP8.x?
My biggest complaint with the standard mail client is on a long email chain on the iPhone 6 regular you have to turn the phone sideways to be able to read the text. The pinch zoom in portrait mode on the client is atrocious too imho.
Oh WP8 well couldn't tell you. Only ever seen one in the wild and the person using it hasn't needed to worry about corporate email for a few decades.