After upgrading to iOS 5, we can no longer fetch POP email.
We have set the account to fetch.
Sometimes we get a message gives the header but no body with an error message that says, "Message not downloaded from server," and sometimes we don't see any sign of the message at all. These are very short messages with no attachments.
We have one iPad 2 that is still running iOS 4.2, and on that one, when you hit the refresh button in the lower left corner of the email window, it fetches any new messages immediately, no problems.
On the iPad 2s we have upgraded, when you hit refresh on the email window, nothing happens. We've tried closing and re-opening mail, rebooting the iPad, tinkering with the mail account settings, and nothing seems to work.