Apple acknowledges iOS 6.1 Exchange bug and has identified a fix
On January 28 Apple released iOS 6.1 and with it, a significant bug that's been giving IT administrators headaches. Almost immediately after 6.1 was released Microsoft Exchange admins began noticing that iPhones and iPads running 6.1 were causing "excessive logging" on the server.
The problem has been traced to Apple code that calls ActiveSync to synchronize a user's Exchange mailbox and calendar events. According to Microsoft iOS 6.1 was responsible for the "rapid growth in transaction logs, CPU use, and memory consumption in Exchange Server 2010 when a user syncs a mailbox by using an iOS 6.1-based device."
Enterprise users are being warned by their IT departments not to use iOS 6.1 devices with corporate servers. Symptoms included email downloading slowly, duplicate calendar items and the inability to delete, edit or move items. Some companies are asking iOS 6.1 users not to connect to their servers, while others are actively blocking iOS 6.1 -- even company-issued devices -- by adding a simple rule to /microsoft-server-activesync which throws a simple "The server refused connection" on the device.