Hi. A group of us have iPhone 5's where we work. Email is Microsoft Exchange. Some of us can send emails from our iPhone's with no problem. Others see intermittent issues where out-going emails are lost (not received by recipient, not in Outbox or Sent items on the iPhone).
We were told to turn off wifi and let cellular handle handle email traffic, so we tried that starting yesterday. Too soon to know, but it looks like it might have fixed the problem. But this solution makes no sense to me.