Apple started rolling out iOS 11 yesterday. The latest update to the company’s operating system packs a wide range of changes and updates, including a new image file format that’ll help save storage. But if you use Apple’s stock Mail app in iOS 11, you will have some issues with your Outlook.com and Office 365 email accounts.
Users with an Outlook.com, Office 365, or Exchange 2016 email account may not be able to send emails using the default Mail app in iOS 11. When trying to send a mail, users will hit the “Cannot Send Mail. The message was rejected by the server.” error. A fix for the issue isn’t available, but Microsoft is recommending users to install the Outlook app for iOS as a workaround. In addition to that, users using Exchange 2016 might be able to workaround this issue by temporarily disabling HTTP/2 in Windows Server 2016.
Both Apple and Microsoft have already acknowledged the issue, and a fix for it will be released with a new update sometime soon: “Apple is working closely with Microsoft to resolve the issue and will release a fix soon in an upcoming software update.”