Millions of Outlook users worldwide entered a second day without reliable email access on November 13, after a Microsoft 365 outage that began shortly after noon ET on November 12 and has yet to be fully resolved. The interruption is a rare event for a communications platform run by a company valued at nearly $4 trillion — and Microsoft has not given a definitive explanation for it.

Some services affected by the incident, including Teams, have been restored. Outlook has not. Government agencies, hospitals, emergency services and schools — not only businesses — reported disruption, because any entity running Outlook and services tied to Exchange Online (Microsoft's cloud email backbone) was hit.

What caused the outage?

There is no confirmed answer. Microsoft's Microsoft 365 Status account on X posted that "we've determined a portion of infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors." That phrasing — "likely contributing" — stops short of a root cause. Other reports point to a possible configuration change, but that theory remains unverified.

In a follow-up post, the account said Microsoft's "investigation indicates the failed health checks may originate from a specific component that's responsible for processing server health." The company's Service Health Status page classifies the event as a "service degradation," confirms that multiple services interacting with Exchange Online and email are impacted, and says "traffic is being gradually restored" with "improvements in key customer scenarios, including mailbox access and delayed email processing." The same notice cautions that "some users may continue to experience intermittent issues."

Microsoft has ruled out one theory outright: "At this time, we have no evidence of malicious activity associated with this incident," the status page states. Fast Company has reached out to Microsoft for comment.

What does this change for IT administrators and business leaders? Very little immediately — recovery depends entirely on Microsoft's engineers — but the vagueness of the updates has become its own problem. A Reddit thread speculated that the impenetrable status language signals Microsoft still lacks a clear picture of the cause. One Reddit user, simAlity, mocked the updates in a widely shared post: "Translation: We ain't got the first clue WTF is going on." On X, user @esrtweet responded to one Microsoft 365 Status update: "Did you just say, right out in front of Goddess and everybody, that it is unpredictable when your cloud servers will stop collapsing under load?"

Are the layoffs and buyouts connected?

Critics have connected the outage to Microsoft's recent staffing decisions, though no evidence yet links the two. In July, Microsoft cut around 4,800 employees. Weeks before the outage, it began offering buyouts to 60,000 workers — more than 25% of its workforce — to help fund its AI infrastructure spending.

"I have no doubt there's a 60 year old engineer out there who took Microsoft's buyout offer from last month that did a bunch of undocumented work his bosses didn't know about to keep things running and could fix this in 2 minutes, but alas Microsoft needs more $$$$ for AI capex," wrote X user @OldManFay12. X user @IAmSoleyman added: "Microsoft has laid off thousands of people while pouring billions into AI. Then Outlook goes down around the world, and for 10+ hours everyone is waiting on human engineers to bring it back." Whether recent departures contributed to the outage or slowed its resolution is currently unknown.

How has MSFT stock reacted?

Microsoft shares (Nasdaq: MSFT) fell roughly 1.5% in premarket trading, to about $515.06 from the previous close of $523. That decline may reflect the outage, but a caveat applies: swings of a few percent are routine for large tech stocks, particularly in recent weeks, when the midterm elections and the Jensen Huang Nvidia scandal have driven volatility across the sector.