For millions of people, Friday 13 November 2026 started the same way Thursday had ended: with an inbox that would not open. Microsoft 365 suffered a major global outage that began on Thursday 12 November and stretched into a second day, knocking out Outlook email and taking down parts of Teams, SharePoint Online and Microsoft 365 Copilot along with it.
Microsoft has confirmed the outage, tracked it under two incident numbers, and says it is not a cyberattack. What it has not yet done — as of Friday morning — is declare the incident fully fixed or publish a root cause. Recovery is under way and email queues are shrinking, but Microsoft’s own status page still warns that service health remains variable.
Summary
- A global Microsoft 365 outage began on Thursday 12 November 2026, starting with Exchange Online mailbox problems in the Americas before spreading worldwide.
- Outlook was hit hardest: users could not open mailboxes on the web, desktop or mobile, and email delivery was delayed. Teams calendars and scheduling, SharePoint Online, Microsoft 365 Copilot and Defender XDR were also affected.
- Downdetector recorded around 138,000 Outlook problem reports at the peak on Thursday afternoon, with reports coming from 74 countries.
- Microsoft says a large number of its own servers became unexpectedly unavailable after failing automated health checks, overloading the servers that were left. It says there is no evidence of malicious activity.
- By early Friday 13 November, Microsoft reported email queues were “significantly reduced and approaching normal levels”, but full restoration had not been confirmed and some users were still seeing delays.
- Microsoft has promised a full post-incident report with the root cause once the problem is fully resolved.
What Went Down
The first sign of trouble was email. Users in the Americas began reporting that they could not reach their Exchange Online mailboxes on Thursday morning, and Microsoft opened an incident for it — EX1550543 — at around 11:17 AM Eastern Time. Within a few hours the problem had widened well beyond one region or one service, and Microsoft opened a second, broader incident, MO1550821, which it lists as starting at 1:26 PM Eastern Time.
The advisory also named SharePoint Online, Microsoft 365 Copilot, Microsoft Defender XDR, Planner, To Do, Intune, Purview and Power BI as affected, and Downdetector logged surging complaints about OneDrive, Azure and the Microsoft Store too. Teams itself was only partly hit: the parts that depend on Exchange — calendars and scheduling — failed, while most Teams chat, calls and meetings kept working.
The scale of the disruption is clearest in the complaint numbers. Reuters reported that Outlook complaints on Downdetector peaked at 138,058 at around 1 PM Eastern on Thursday, and the BBC reported that 140,000 people from 74 countries reported Outlook problems that afternoon. Hospitals, airports, GP surgeries, pharmacies, schools, police forces and parliaments were among those reporting problems, and staff in the US House of Representatives were affected. One company, Workhorse Group, even postponed its third-quarter earnings report from 12 November to 16 November because of the outage.
For most users the symptoms were the same: Outlook on the web would not load or showed that it could not reach the internet, the desktop app opened but showed only previously downloaded mail, and new messages simply did not arrive. Some people found Teams working but email dead; others could open OneDrive but not Outlook. Which services failed depended on which of Microsoft’s servers a user’s organisation was served from.
What Microsoft Says Caused It
Microsoft’s explanation has shifted as its engineers have learned more. At first, the Microsoft 365 Status account blamed “elevated load across multiple regions” for the connectivity errors. Later updates changed the picture: Microsoft said a large number of its servers had become unexpectedly unavailable, and the remaining infrastructure buckled under the extra traffic those missing servers left behind. More specifically, Microsoft said a core process that sets up secure connections was becoming overwhelmed, and affected servers were failing automated health checks — the routine checks that decide whether a server is healthy enough to take traffic. When servers fail those checks they drop out of service, which piles more load on the ones that remain. Microsoft has not yet confirmed a single root cause, but it has ruled out one popular theory: a company spokesperson told the ABC there was “no indication this is a cyber attack”, and Microsoft executive Charles Lamanna wrote on X late on Thursday that there was no indication the outage was “the result of malicious or cyber activity”.
There is also an unconfirmed report about the cause that should be treated as exactly that — a report. The Verge’s Tom Warren said on X that his sources linked the outage to configuration changes in Azure Virtual Network, Microsoft’s cloud networking service. Microsoft has not confirmed that. Australia’s Home Affairs Minister, Tony Burke, told reporters that Microsoft believes it is dealing with something similar in some ways to the 2024 CrowdStrike incident — a minister’s characterisation, not a published root-cause finding. The final word will be Microsoft’s own post-incident report, which the company has promised to publish after mitigation is complete.
How Recovery Is Going
Recovery has been slow and uneven, and Microsoft has been unusually open about that. In an update at 6:57 PM Eastern on Thursday, the company said it was seeing “limited recovery” after successfully returning some affected servers to service, and that those servers were remaining stable. But its fixes did not all work as planned: Microsoft later admitted its initial fixes were “not taking as expected”, and engineers moved to alternative approaches.
By early Friday, the picture had improved without being resolved. In an update at 5 AM Pacific on Friday 13 November, Microsoft said it was seeing “broader improvements now observed in North America and sustained improvements across much of Europe”, along with early signs of recovery in Asia Pacific. Email queues were “significantly reduced and approaching normal levels”, though some users could still have trouble getting in or see delayed messages. Microsoft also extended its email timeout window to 48 hours to help preserve messages delayed by the outage.
What Microsoft did to get there is also on the record. The company said it paused all deployments, redistributed connection traffic across its worldwide infrastructure, and moved traffic away from affected systems to reduce load. It is restarting affected servers to restore capacity, and it applied an upstream authentication and routing configuration patch to part of its infrastructure. Even so, its status page on Friday morning still carried the message that users “may be unable to connect to multiple Microsoft 365 services”, and Microsoft has given no time for full recovery.
What To Do If You Are Still Affected
If your Outlook still will not connect, the first thing to know is that the problem is almost certainly not your computer, your internet connection or your password. Do not reset your password or reinstall Outlook in response to this outage — neither will fix a server-side failure.
The practical steps are simple. Check Microsoft’s status page at status.cloud.microsoft, or Service health in the Microsoft 365 admin centre, and follow incidents MO1550821 and EX1550543. If you use the Outlook desktop app, your previously downloaded mail should still be readable even while new mail is delayed. If a message is urgent, use another channel — Teams chat and meetings have mostly kept working through the outage.
For businesses, the outage is also a reminder worth acting on once service is back: keep an out-of-band way to reach staff and customers, and make sure critical contacts are stored outside the mailbox. For now, the advice is to wait for Microsoft’s all-clear rather than troubleshoot your own setup. The email backlog is clearing, the servers are coming back, and the company’s own updates are the only reliable source for when your mailbox is fully back.
Sources: BleepingComputer (12 Nov 2026); The Verge via GeekWire and ChannelPro Network (13 Nov 2026); BBC via People (13 Nov 2026); Microsoft 365 Status updates, incidents MO1550821 and EX1550543.
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FAQs
Q1. What caused the Microsoft 365 outage in November 2026? — Microsoft says a large number of its servers became unexpectedly unavailable after failing automated health checks, which overloaded the remaining infrastructure. A core process that sets up secure connections was becoming overwhelmed. Microsoft has not yet published a confirmed root cause and has promised a full post-incident report once the problem is fully resolved.
Q2. Which Microsoft 365 services were affected by the outage? — Outlook and Exchange Online were hit hardest — users could not open mailboxes or send and receive email. Microsoft also listed Teams calendars and scheduling, SharePoint Online, Microsoft 365 Copilot, Defender XDR, Planner, To Do, Intune, Purview and Power BI as affected. Most Teams chat, calls and meetings kept working.
Q3. When did the Microsoft 365 outage start? — The outage began on Thursday 12 November 2026. Microsoft opened an Exchange Online incident (EX1550543) at around 11:17 AM Eastern Time after mailbox problems in the Americas, and a wider Microsoft 365 incident (MO1550821) starting at 1:26 PM Eastern Time. It continued into Friday 13 November.
Q4. Was the Microsoft 365 outage a cyberattack? — No, according to Microsoft. The company says it is not aware of any malicious activity behind the outage, and Microsoft executive Charles Lamanna confirmed on X that there was no indication it was the result of malicious or cyber activity. An unconfirmed report linking it to Azure Virtual Network configuration changes has not been confirmed by Microsoft.
Q5. Is the Microsoft 365 outage fixed now? — Not fully, as of Friday morning 13 November 2026. Microsoft reported email queues were significantly reduced and approaching normal levels, with broader improvements in North America and Europe, but service health remained variable and full restoration had not been confirmed. Check status.cloud.microsoft or incidents MO1550821 and EX1550543 for the latest position.
