Apple, Microsoft patch iOS 11 email flaw

A glitch in iOS 11 that sporadically left some Microsoft email users unable to send messages has been fixed.

Credit: Computerworld / Apple

A flaw in iOS 11 that left some users of Microsoft email unable to send messages has been fixed, the companies said.

Email accounts hosted by Microsoft on, Office 365, or an Exchange Server 2016 running on Windows Server 2016 were affected by the software glitch.

Some users of mobile devices running iOS 11 have been receiving error messages that read: "Cannot Send Mail. The message was rejected by the server."

The problem was noted by Apple iOS 11 users in a post on

On Sept. 19, Apple published a support document stating it was working with Microsoft to fix the issue, which was described as iOS 11 not being able to successfully create an HTTP/2 Transport Layer Security connection; that kept it from connecting to email clients and prohibited outgoing email from being delivered.

Apple has updated its support document, stating that upgrading to iOS 11.0.1 or later will fix the problem.

"It’s certainly a big problem for users, especially business users, who rely on their mobile devices," said Jack Gold, principal analyst at J.Gold Associates.

The sporadic nature of the glitch makes it difficult to pinpoint how many users were affected by the issue, but Gold noted that most users upgrade to newer OSes almost as soon as they come out, making it likely that a large universe was affected. Regardless, Gold added, "it's never a good idea to have such problems that annoy users greatly."

Before upgrading a device, users should verify that it is compatible with iOS 11.0.1.

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