Microsoft 365 outage drags on, but things are improving

Microsoft’s efforts to fix what is now a multi-day outage affecting customer access to Outlook email and other Microsoft 365 services entered a second day Tuesday. The company made significant progress addressing the problem on Monday, after an issue impacting its Exchange Online service caused email delays and failures, authentication issues, and other problems for some Outlook users. But as of Tuesday the issues were still not fully resolved; Microsoft’s latest update on X said its “mitigation actions are continuing to progress” — not quite the same as saying all was well.

While Outlook received most of the attention, Microsoft’s status page for Microsoft 365 (Business or Enterprise) indicated that other services were ultimately affected too, including SharePoint, Copilot, Teams, Purview, Defender XDR, the Microsoft 365 Admin Center, and Universal Print, attributing the problems to an issue with a “core authentication configuration used by multiple Microsoft 365 services.” Overnight, Microsoft shared on X the steps it was taking to resolve what its investigation found was a misconfiguration issue, saying the problem was preventing authentication components from “deploying as expected to a portion of infrastructure.”

Microsoft said it first reviewed recent changes that could have caused the problem, then tested and implemented various mitigations to relieve end users; as those mitigations rolled out, the company said Outlook users should see “gradual recovery” in their mail flow. By 10 p.m. ET on Monday, Microsoft said mail flow was improving, though search functionality remained degraded; shortly after 3 a.m. ET on Tuesday, it said it was seeing improvements there too. While many users were likely seeing improvements by then, Microsoft had not yet said its service was back to normal.

Microsoft’s latest message on X said “indications from telemetry remain positive” and that service availability was improving, adding that it was now entering a period of extended monitoring to ensure a full resolution.

Why it matters

A single authentication misconfiguration knocking out Outlook, Teams, SharePoint, and Copilot at once for more than a day underscores how concentrated the risk has become now that so many workplace tools sit behind one shared identity layer.