Major Exchange Online Outage: Emails Fail to Arrive, Sign-In Won't Work

Microsoft has reported a major outage affecting its cloud-based email service, Exchange Online. The incident, logged in the admin center under the number EX1464935, has hit authentication, message delivery and other platform features. The company confirmed the problem at 17:30 UTC, after a wave of complaints began building on social media.

According to the monitoring service Downdetector, tens of thousands of users felt the outage: they were unable to receive email through Outlook or to sign in to the Exchange Online platform itself.

What exactly is broken

Microsoft listed the symptoms of the trouble:

• delays and failures when sending and receiving email;
• slow, incomplete or non-functioning search across mailbox contents;
• authentication errors when accessing Exchange Online services;
• difficulty reaching Exchange administrative interfaces and carrying out actions within them;
• intermittent failures of mailbox operations and message delivery processes.

The company has not yet named the regions that were affected, but has classified what is happening as an “incident” — a category used for critical problems with a noticeable impact on users.

“We've isolated a common failure pattern in the affected Exchange Online requests, related to authentication and protocol-based connectivity,” the latest admin center update states. Engineers are analyzing service telemetry to pinpoint the root cause and to test possible mitigation options, and they continue to assess the scope of the problem.

Not the first time this year

Over the past few months, Exchange Online has been rattled more than once. In June, Microsoft addressed a failure in the mail delivery pipeline that affected customers in North America, the Asia-Pacific region and Europe. In April, the company was dealing with two problems at once: one intermittently prevented Outlook users on mobile devices and macOS from accessing their mailboxes for weeks, while the other blocked access to email via Outlook on the web, the desktop application, Exchange ActiveSync and other connection protocols.

As of publication, the story was still developing: Microsoft had not yet reported that the issues were resolved.

Source: Bleeping Computer