Microsoft published a statement today regarding the iOS11 vs. Exchange/Outlook problem:
In the native Mail app (Mail.app) on your iPhone or iPad, you can't send or reply from your Outlook.com, Office 365, or Exchange Server 2016 email account after you upgrade to iOS 11.
Note These issues don’t occur in iOS 10.
This issue occurs because the Mail app on iOS 11 is not compatible with Outlook.com, Office 365, or Exchange Server 2016 running on Windows Server 2016.
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.
Microsoft and Apple are working to resolve this issue and will post more information to the article when it becomes available.
OIT will post updates as we become aware of them. To view the entire article, visit: