Apple says it is working closely with Microsoft to fix an issue that prevents Outlook.com, Office 365, and Exchange 2016 account holders from sending or replying to emails using the Mail app in iOS 11.
Apple published a support document on Tuesday, September 19 to acknowledge the issue affecting users of Microsoft email servers.
Apple is working closely with Microsoft to resolve the issue and will release a fix soon in an upcoming software update. – Apple Support
Microsoft also published a support note, which states that Apple’s Mail app in iOS 11 “is not compatible with Outlook.com, Office 365, or Exchange Server 2016 running on Windows Server 2016”.
It looks like they may not have read flagged messages by the Mail app problem in iOS 11. Several users who installed beta builds of the iOS 11 flagged the issue with Apple as far back as July.
Despite potentially being aware of the problems for some time, both Apple and Microsoft say they’re still working together to resolve the issue. Apple added that it would release a fix soon in the form of an upcoming software update, while Microsoft offered the following workaround in the meantime:
To work around this issue, download the free Outlook for iOS client from the App Store. The Outlook for iOS client fully supports various email services, including Outlook.com, Office 365, and Exchange Server 2016.