The new iPhone OS has several problems when connecting to Exchange. The Microsoft Online Services Team Blog gave some information about the problem and send out an e-mail how to solve the problem:

On July 22, we published a notification to the Microsoft Online Services Team Blog about a forthcoming requirement for users connecting to Exchange Online via iPhone devices. And we want to make sure you are aware of this requirement.

Apple recently released iOS 4.0.1, an update for the iPhone operating system. iOS 4.0.1 is available for iPhone users with iPhone 3G, 3GS and 4 devices. To deliver the best possible service experience, Microsoft Online Services is requiring users with devices running iOS4.0.0 to update their devices to iOS 4.0.1 by Thursday, July 29. Information about installing iOS 4.0.1 can be found in the Apple support knowledgebase, Article DL1061.

iOS 4.0.1 includes updates for several issues, including the configuration patch needed for iOS4 devices to use Exchange ActiveSync with Exchange Online. We reported about the configuration patch in a previous post to the Team Blog, and Apple confirmed the problem and remediation offered by iOS 4.0.1 in the Apple support knowledgebase, Article TS3398.

After July 29, users that have not updated iOS4 devices to iOS 4.0.1 will be unable to connect to Exchange Online via Exchange ActiveSync to send and receive email and synchronize message and calendar items. This only affects users with devices running iOS4; devices with previous versions of Apple iOS are unaffected.

The Microsoft Online Services team is committed to providing the highest quality service experience to our customers. Organizations that have questions should not hesitate to contact Microsoft Online Services Technical Support.