This is one of those bugs that I hope will be fixed in every iOS update that comes out, but so far the problem lingers.
Here’s the problem:
You load up the Mail app and start browsing through you messages looking for a new one to read. You tap on an entry. The header information loads up into the window and… that’s it.
I’m not sure how it happens, but the app gets to where it just won’t download (or just won’t display) the body of the message. Kind of annoying.
Workaround 1 (fast):
Hit the Reply button.
The reply window will appear and the body of the message will have been copied into the reply. The good news is that now you can see what was written, and you’re also a step ahead if you do in fact want to reply. The bad news is that you’re going to have to keep doing that for every message you want to read unless you try…
Workaround 2 (takes a little longer):
Hit the home button twice (or do a four finger swipe up if you have advanced gestures enabled) so that you can see the list of running app icons along the bottom of the screen. Find the Mail icon. Put your finger on it and hold it there until the icons start to wiggle, like you would if you wanted to rearrange the apps on your home screen. A little X will have appeared on the icon. Tap this X and it will end the task and remove the app from memory so it gets a clean start the next time you run it. Fire the app back up and now it should display messages correctly as you select them from the list.