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Microsoft's Outlook email service went down for users around the world on Thursday, November 12, in a major outage that also disrupted Teams, SharePoint and Copilot, with outage tracker Downdetector logging problem reports from 74 countries. The disruption began at about 4:17 p.m. UTC on Thursday and was still not fully fixed on Friday morning, November 13.
The fault sits in Exchange Online, the cloud service behind Outlook mailboxes for most businesses, schools and government offices. At the peak, Downdetector recorded more than 120,000 Outlook problem reports, and at one point 19,650 reports a minute across five Microsoft services, against fewer than 15 on a normal Thursday. Microsoft 365, the subscription service that includes Outlook and Teams, has more than 430 million users, and the outage left businesses, schools and government departments struggling to reach their email, with some also losing Teams meetings, SharePoint files and Copilot.
Microsoft says the outage was not a cyberattack and that it is not aware of any malicious activity. Charles Lamanna, an executive vice president at the company, said there was no indication of a security breach, and Australia's Home Affairs Minister, Tony Burke, said Microsoft had told him it did not believe a cyber event was involved. Microsoft has not confirmed a root cause. It says a process that establishes secure connections on the affected servers became overwhelmed, leaving the servers unable to handle requests, and that a large number of servers failed automated health checks and became unavailable. Engineers have begun reversing a recent network configuration change that lines up with when the problems started, rebuilding some servers on an older software configuration and deliberately limiting some kinds of traffic. Microsoft has also extended its email timeout window to 48 hours to protect delayed messages, and says it will publish a full post-incident report once services are restored.
Recovery has been uneven. By Friday morning, Microsoft had restored service in some regions, but some servers that came back went down again, and the company had given no time for full restoration. Microsoft is tracking the wider Microsoft 365 disruption as incident MO1550821 and the Exchange Online disruption as EX1550543.
Security experts warn that the outage itself creates a second risk. Scammers exploit major disruptions with fake messages telling users to verify, restore or recover their Microsoft account, linking to convincing copies of the Microsoft login page. McAfee, which has tracked such campaigns springing up within hours of past outages, advises users to check only Microsoft's own status page or its verified @MSFT365Status account, and not to click unexpected links or share passwords or verification codes in response to an unexpected message.