Parallels Desktop 8 for Mac is lets you seamlessly run Windows and Mac applications side-by-side

Apple discloses iOS bug with Exchange Server; MS advises to block iPhones

By John Rizzo

Apple has posted a warning of a bug in iOS 6.1 that causes "excessive communication" with Exchange Server, so much that the server could block the iPhone, iPad, or iPod touch from accessing it. The problem can also degrade server performance. Apple described how to avoid the problem and promises a fix.

Microsoft also offered a workaround, but went further by recommending that administrators create a "throttling policy" to limit communications from iPhone, and to block iPhone connections completely in order to prevent degredation of server performance.

Apple said that when a user syncs a mailbox by using an iOS 6.1-based device, Microsoft Exchange Server 2010 Client Access server (CAS) and Mailbox (MBX) server resources are consumed, log growth becomes excessive, memory and CPU use may increase significantly, and server performance is affected.

Apple said the iOS 6.1 bug manifests when a device user makes a change to a single instance of a recurring calendar event. The user then receives an "exception" message. If the user responds to the message, the iOS device then begins its "excessive communication" with Exchange Server (either Exchange 2010 SP1 or later, or Microsoft Exchange Online, which is also known as Office365).

Microsoft said that the calendar problem manifests itself when a user syncs a mailbox, and that the server performance can degrade:

When a user syncs a mailbox by using an iOS 6.1-based device, Microsoft Exchange Server 2010 Client Access server (CAS) and Mailbox (MBX) server resources are consumed, log growth becomes excessive, memory and CPU use may increase significantly, and server performance is affected.

Apple said the user can avoid the problem by not responding to the exception message. If the problem does occur, Apple advises users to disable, then re-enable, the Exchange calendar on the iOS device:

  1. Go to Settings > Mail, Contacts, Calendars Select the Exchange account from your Accounts list.
  2. Turn the switch for Calendars to OFF.
  3. Wait ten seconds.
  4. Turn the switch for Calendars back to ON.

Microsoft's workaround for the iPhone goes further:

  1. On the iOS 6 device, instruct the user to remove the Exchange account.
  2. On a system that is running the Exchange Management Shell, the Exchange Server administrator can run the Remove-ActiveSyncDevice cmdlet to remove the device on the server-side. See the Remove-ActiveSyncDevice topic in Microsoft TechNet online.
  3. Wait 30 minutes, and then instruct the user to add the Exchange account to the device. Advise users not to process Calendar items on the device.

The Microsoft support article goes on to say, "You can block iOS 6.1 users by using the Exchange Server 2010 Allow/Block/Quarantine feature."

Apple said that it would supply a fix in an update to iOS 6.

Have you seen this problem? Please