WHAT'S HAPPENING?
Microsoft announced incompatibilities between iOS 11 native mail applications and Office 365 Exchange services.


WHEN IS IT HAPPENING?
Tuesday, September 19, 2017, and ongoing.


WHY IS IT HAPPENING?
According to their support article [https://support.microsoft.com/en-us/help/4043473/you-can-t-send-or-reply-from-outlook-com-office-365-or-exchange-2016-i], iOS 11 introduced incompatibilities with Outlook.com, Office 365, or Exchange Server 2016 running on Windows Server 2016.  Microsoft and Apple are actively working to resolve this issue.  More information and tracking of this issue is available at https://status.gatech.edu/.


WHO IS AFFECTED?
Any user of iOS 11 native mail applications and Office 365.


WHAT DO YOU NEED TO DO?
It is recommended to either avoid upgrading to iOS 11 or to use the Outlook for iOS client available in the App Store.


WHO SHOULD YOU CONTACT FOR QUESTIONS?
Feel free to contact the TSO Help Desk (CCB 148, 404.894.7065, helpdesk@cc.gatech.edu).  If you prefer, you may contact the OIT Technology Support Center (404-894-7173, support@oit.gatech.edu).

UPDATE: Apple has resolved this issue with iOS version 11.0.1.