Microsoft Exchange mobile users on Android and iOS users have been unable to access the service on their mobile devices due to a planned shift away from its Exchange Active Sync (EAS) protocol.
The issue first appeared yesterday and is still affecting users.
One customer got in touch to say: "Exchange Mobile device access seems to be up the Swanny for iOS and Android users." They quipped: "Fortunately neither of the Windows Mobile users are affected."
An error note to users reads: "Device access rules cannot currently be enforced on Outlook for iOS and Android. We are working on re-enabling it. In the meantime, please reach out to Microsoft Support if you wish to block the app."
Microsoft said the issue was due to a planned transition for iOS and Android customers from EAS email synchronization to a REST-based system. "Some customers may temporarily be unable to enforce device access rules," said a spokesman.
"While the transition is in progress, customers who wish to block the application should contact Microsoft Support. For more information, customers can visit the Service Health Dashboard within their Office 365 Admin Center."
The move appears to be an attempt by Microsoft to ensure people continue to use Exchange in the workplace and see off the threat posed by Google Docs. Third parties had to license the XML-based EAS while REST is free.
That licensing approach worked fine in a world where Microsoft with Exchange essentially owned enterprise email and collaboration platforms, but developers can now sidestep Exchange thanks to the presence of free - nominally at least - open-source and web-based alternatives.
By shifting the protocol, it is also hoping developers continue to build apps for Exchange and Office 365 by getting a REST-based system for free rather than having to pay a licensing fee.
In a blog last year Microsoft said:
Exchange ActiveSync is different from the Office 365 Outlook REST APIs. Exchange ActiveSync is highly optimized for mobile clients connecting directly to Office 365/Exchange Online, and requires a licensing fee to use.
The Outlook REST APIs are standards-based REST+JSON+OAuth Mail, Calendar, and Contact APIs that have no licensing fee, and are great for both mobile device-to-Office 365/Exchange Online, and service-to-Office 365/Exchange Online applications. We recommend that developers explore and evaluate the Outlook REST APIs for their application.