A widespread Microsoft 365 outage has disrupted Outlook email access and affected parts of Teams, Copilot and other workplace services, with Microsoft working to restore servers that keep becoming unresponsive.
The problems began on Thursday 12 November 2026 and continued into Friday morning in the UK. Microsoft has reported limited recovery in some regions, but has not confirmed when normal service will be fully restored.
Latest checked: 00:30 GMT, Friday 13 November 2026.
Which Microsoft services are affected?
The main disruption involves Exchange Online, which powers email and calendar services for many Microsoft 365 business and organisational accounts. Depending on how they connect, affected customers may be unable to open Outlook mailboxes, send or receive email normally, or access calendars. Email delivery may be delayed.
Microsoft’s incident advisory, MO1550821, says other affected functions include:
- Microsoft Teams: calendar-related functions, meeting scheduling and some organisation-specific chat creation may fail. Microsoft says core messaging and online meetings remain largely functional.
- Microsoft 365 Copilot: some users may have trouble loading chats or accessing work data.
- SharePoint Online: features relying on Exchange Online may be affected, although direct access to stored files remains functional.
- Microsoft Planner and To Do: loading and task operations may fail.
- Microsoft Defender, Purview and other administration tools: some portals and connected features may be unavailable or degraded.
Microsoft said an earlier, separate Teams messaging incident affecting North and South American regions had been resolved. That should not be confused with the ongoing Microsoft 365 incident.
What caused the Microsoft outage?
Microsoft’s investigation has found that a large number of servers unexpectedly became unavailable, leaving working infrastructure to handle more requests. A process on the affected servers was becoming overloaded, and some servers were failing automated health checks.
Engineers have moved some traffic to alternative routes, restarted infrastructure, isolated parts of the service and tested older software configurations. By late Thursday, some servers had returned to service, but Microsoft subsequently warned that they could become unresponsive again when traffic resumed.
The company is investigating whether recent configuration updates contributed to the problems. It has not yet confirmed a definitive root cause.
Was the outage caused by a cyberattack?
There is no verified evidence at this stage that the outage was caused by a cyberattack. Microsoft has described server, health-check and capacity problems, and is investigating potential configuration-related causes. That does not establish malicious activity, and speculation about hacking should not be presented as fact.
How widespread is the disruption?
The outage has affected customers across multiple regions, with major reports from the Americas and disruption to connected services elsewhere. The Associated Press reported that Downdetector recorded nearly 130,000 reports of Outlook problems shortly after 1pm US Eastern time on Thursday, equivalent to just after 6pm GMT. Those reports are user-submitted signals, not a verified count of people affected.
Reuters also reported disruption to Microsoft integrations used by OpenAI and Anthropic, underlining the effects on services that rely on Microsoft’s systems.
What should affected users do?
Businesses should check Microsoft’s public cloud service status page and, where accessible, their organisation’s Microsoft 365 Service Health dashboard for incident EX1550543 and related advisory MO1550821. Administrators can use an unaffected communication channel to keep staff informed.
Repeatedly changing passwords or reinstalling Outlook is unlikely to solve a confirmed Microsoft-side infrastructure outage. Users should avoid assuming that a delayed email was delivered successfully until it appears in the sent items or the recipient confirms receipt.
When will Outlook and Teams be back to normal?
As of the latest Microsoft advisory reviewed shortly after midnight GMT on Friday, recovery remained incomplete and no firm restoration time had been announced. Some services may return gradually as server capacity is restored and connections recover.
Follow this story: See our Microsoft 365 outage updates for further developments.
Sources
- Microsoft Cloud Service Status and incident advisories EX1550543 / MO1550821.
- University of Pennsylvania, Microsoft 365 incident notices, reproducing official service updates.
- University of Wisconsin-Milwaukee, Microsoft outage updates.
- Associated Press, outage reporting.
- Reuters, disruption to Microsoft 365 and integrations.
