Following Apple’s iOS11 update on 19th September, several users have reported issues with the standard iOS Mail application not connecting to Exchange Online or Outlook.com, which can be a very frustrating issue if you use the Mail app to access your Outlook account.
Why is this happening?
The problem lies in the connection that Exchange 2016 uses to connect the app with iOS mail servers, as it uses HTTPS/2 TLS connections. The iOS Mail app attempts to connect to Exchange, finds out that it can’t and leaves your Mail app in a position where it can’t do very much.
Microsoft is currently advising that the only solution for these users is to disable HTTP/2 on the server but this in turn can’t be done for Office 365 users as they won’t have access to the system registry.
Now, some users on iOS11 are having no issues, but it doesn’t mean that the problem doesn’t exist. With users connecting to Exchange 2016 mailboxes through any one of the 100,000 mailbox servers, it’s possible that you could latch onto one that successfully achieves a connection – great news!
So what can be done?
While Apple has identified the issue and is working on a solution, the only advice that they are currently offering is to consider using the Outlook for iOS app, which in turn requires storage space and is another application that users would need to run.
The key here, unfortunately, will be patience while this error is addressed with the next iOS11 upgrade. We have been assured that it isn’t affecting users on previous iOS systems.