Many MindedMicrosoft cloud outage stalls email and device management as recovery falters
A Microsoft cloud outage that began around 18:00 UTC on 12 November 2026 made Exchange Online, Teams, Copilot 365 and Defender for Office 365 unavailable. Admin tools, including Intune and the Microsoft 365 Apps Admin Center, went down too, which made diagnosis harder. According to The Register's contacts, email was not flowing for many Microsoft customers.
Microsoft attributed the problem to servers failing automated health checks and dropping out of service. Its status page said a core process on affected servers was becoming overwhelmed, so servers stopped responding and capacity was lost. Early investigation pointed to a component that processes server health as a possible origin of the failed checks. Microsoft said it had found no system changes that could have triggered the incident, though it was assessing whether reverting a few recent configuration updates might speed recovery.
Around 22:00 UTC, an alternative health check method returned a subset of servers to service, but Microsoft said its actions had not delivered the relief it expected. Its latest approach was to isolate part of the infrastructure, restart components and reintroduce traffic before a wider rollout. An update at 00:35 UTC on 13 November said some restored servers stayed healthy at first but could stop responding again once traffic returned. Engineers were analyzing diagnostic data with networking and platform experts to find the trigger.
The episode shows the cost of concentration. When one provider hosts mail, collaboration and the tools used to manage devices, a single fault can cut off communication for many organizations at once, and the loss of admin tooling slows their own response. That is a setback for reliable, basic connection.
Watch for a restoration timeline, which Microsoft has not given, and for a confirmed root cause. The stated cause is preliminary, the status page information was described as contradictory, and the number of affected customers has not been quantified. The situation was still developing.
Source: The Register