Mysterious. This helpful post didn’t solve it for me in iOS 5.1.1.
I have researched this non-stop and I will report when I have found a solution. I got tired of looking for a solution and called Applecare and paid them $50 to fix the issue. Their fix? To restore the iPhone as a new device and setup the email account from scratch.
To fix this I have tried and didn’t work:
- To restart the iPhone 5.1.1
- To close the Mail program by tapping the home button and clicking ont the X to close it.
- To turn off the mail in the Mail settings by clicking on the account and clicking off.
- Doing the same as #3 but restarting the phone.
- Doing the suggestion above to turn off threading.
- Trying to change the number of messages that it retains, and turning off the time that it remembers from one month to a week.
- Doing the #3 suggestion and waiting a minute before turning it back on.
- Doing a hard reboot by holding down the home and top button until the Apple symbol appears.
- Syncing iPhone to iTunes.
- Synchronizing my Exchange account.
- I selected each message under the Edit button at the top right. Then I said Move.