Please, Apple! (yeah, I know I'm not really talking to Apple, here-- I'm just screaming into the abyss of our beloved user-to-user community...)
The connection to WHAT server failed?
Can the darned error message not at least tell us which of several email servers to which we've connected iOS Mail has failed?
For me, the single greatest benefit to my 2 iPads and an iPhone is the ability to co-mingle multiple email accounts into Apple Mail's single, unified inbox view. This benefit greatly diminishes when I get repeated "Cannot get mail" errors that tell me nothing else -- and then sometimes even spontaneously reboots!
I experienced this with iOS 8.1 and 8.2, but it's even more frequent with 8.3.
That stupid MS Surface is looking more and more inviting, every day. Windows devices may crash at least as often as the iPad (and my Mac), but at least they tell me why, so I can try to fix them!