Microsoft is making progress restoring Outlook after a widespread outage disrupted access to email and several other Microsoft 365 services. The company says some affected servers have returned to service and are remaining stable, but recovery is still underway, meaning users could continue running into connection problems.
The trouble began on Thursday, November 12, with Microsoft investigating reports of users struggling to access their Exchange Online mailboxes through multiple connection methods across the Americas. The company later confirmed that the problem could affect Microsoft 365 connectivity in any region. Microsoft’s latest updates suggest that the situation is improving, but the service isn’t quite out of the woods yet.
What caused the Microsoft Outlook outage?
Microsoft initially pointed to elevated loads across multiple regions as a likely reason behind the connectivity errors. However, its investigation revealed that this wasn’t simply a case of too many people trying to access their inboxes at once. Instead, a number of servers had unexpectedly become unavailable, putting additional pressure on the remaining infrastructure.
The company later found that affected servers were failing automated health checks, preventing them from remaining available. Microsoft said the failures may have originated from a specific component responsible for processing server health. It also noted that it hadn’t identified a recent change that clearly correlated with the start of the outage.
Microsoft tried several ways to limit the disruption, including pausing deployments, redirecting traffic away from affected infrastructure, restarting servers, and testing an alternative health-check method. It also explored whether reverting a small number of recent configuration updates could help speed up recovery. However, its initial mitigation efforts didn’t provide the expected relief, prompting the company to isolate parts of its infrastructure, restart affected components, and gradually reintroduce traffic.
Outlook is recovering, but Microsoft 365 users may still face problems
The good news is that Microsoft has begun returning affected servers to service, with some already remaining stable. It’s also rerouting traffic through alternate infrastructure and speeding up recovery efforts. However, the company warns that users may see a gradual restoration as their Outlook and other Microsoft 365 clients reconnect.
The disruption extends beyond Outlook, affecting services including Teams, SharePoint Online and Microsoft 365 Copilot. Microsoft is tracking the incidents under EX1550543 and MO1550821, with updates available through the Microsoft 365 status page. Downdetector recorded nearly 130,000 reports of Outlook problems at the peak, although these are user-submitted reports, not a confirmed count of affected customers.
While the declining reports and returning servers are encouraging signs, the outage isn’t fully resolved yet. Some users may get their inboxes back before others, so a little patience may still be needed.