look at the original email to copy some data, how do I get back to the email I am composing or is it lost?
Before going back to the original email or any other email you must first save the draft of the email you are working on.
Tap Cancel in the upper left corner then tap Save Draft. Be careful because Delete is the other choice and it is physically very close to the Save Draft option.
That's what I thought. The OS should auto save it as a draft if you navigate away from it.
Retrieving data ...