Microsoft 365 Outage Continues Into Second Day as Mitigation Efforts Progress

Microsoft’s efforts to fix what is now a multi-day outage affecting customers’ access to Outlook email and other Microsoft 365 services are entering day two.

The company made significant progress in addressing the problem on Monday, after an issue impacting its Exchange Online service led to email delays and failures, authentication issues, and other problems for some Outlook users.

But as of Tuesday, the issues still are not fully resolved. Instead, Microsoft’s latest update shared on X says its “mitigation actions are continuing to progress,” which isn’t exactly the same as saying “all is well.”

While Outlook received most of the attention, Microsoft’s status page for Microsoft 365 (Business or Enterprise) indicates that other services were ultimately affected as well, including SharePoint, Copilot, Teams, Purview, Defender XDR, the Microsoft 365 Admin Center, and Universal Print.

The page attributed these to an issue with a “core authentication configuration used by multiple Microsoft 365 services.

Overnight, the company shared on X the steps that it was taking to resolve what its investigation found was a misconfiguration issue impacting its service. Microsoft said the problem was preventing authentication components from “deploying as expected to a portion of infrastructure.”

Microsoft had first reviewed the recent changes that could have led to this problem, then it tested and implemented various mitigations to try to provide relief to end users. Over time, as these mitigations rolled out, Microsoft said Outlook users should see “gradual recovery” to their mail flow. By 10 p.m. ET on Monday, the company said that, while mail flow was improving, search functionality remained degraded.

Shortly after 3 a.m. ET on Tuesday, Microsoft said it was seeing improvements with the search functionality.

While many users are likely seeing improvements by now, Microsoft has not yet said its service is back to normal.