Apple has published a support article letting users know that an iOS 6.1 bug fix is coming that will correct Exchange server issues users have been having. In the support article Apple details the symptoms of the bug:
When you respond to an exception to a recurring calendar event with a Microsoft Exchange account on a device running iOS 6.1, the device may begin to generate excessive communication with Microsoft Exchange Server. You may notice increased network activity or reduced battery life on the iOS device. This extra network activity will be shown in the logs on Exchange Server and it may lead to the server blocking the iOS device. This can occur with iOS 6.1 and Microsoft Exchange 2010 SP1 or later, or Microsoft Exchange Online (Office365).* An exception is a change to a single instance of a repeating calendar event.
If you do experience the symptoms described above, disable then re-enable the Exchange calendar on your iOS device using the steps below.
- Go to Settings > Mail, Contacts, Calendars
- Select the Exchange account from your Accounts list.
- Turn the switch for Calendars to OFF.
- Wait ten seconds.
- Turn the switch for Calendars back to ON.