Tens of thousands of users lost email access on Thursday, Nov. 12, 2026, when a major software failure disrupted Microsoft Outlook and Teams for more than five hours.
In the United States, the broadcaster PIX11 reported that more than 100,000 reports came in within the span of just one hour. The disruption, which Microsoft attributed to “increased load” on the infrastructure, lasted for a large part of the American workday.
Van La Défense (Hauts-de-Seine) to offices in Paris, it proved to be a difficult evening for everyone working with Microsoft 365, as personal addresses like Hotmail, Live, or Outlook.com also saw users report on social media that emails to these addresses were refused.
The incident affected 74 countries and territories within a single hour, according to data cited by Nieuws.nl. The disruption touches both private and business users of Microsoft 365, while Dutch users reported on the website Allestoringen.nl that they could not reach the services or had difficulty doing so.
Downdetector recorded a peak of 138,058 user complaints regarding Outlook at 1:00 p.m., while Downdetector registered around 200,000 user reports at the peak of the problems shortly after 1:00 p.m. New York time. An earlier post on X indicated that users in every region could experience issues.
Exchange Online postboxes bore the brunt of the failure, according to a Microsoft spokesperson cited by MarketScreener Nederland. The software company registered the incident under code EX1550543 in its corporate admin center, as noted by Sortir à Paris.
According to Microsoft, multiple servers unexpectedly failed, causing the remaining servers to process more work and become overloaded.
Traffic was systematically rerouted through alternative pathways while engineers attempted to bring the disabled servers back online safely, MarketScreener Nederland reported. The software manufacturer acknowledged that initial mitigation steps failed to produce the expected resolution.
“We continue to pursue all available avenues to restore service, as the mitigations we’ve taken so far have not provided the expected resolution,” the company said, according to Headliner.nl.
Engineers identified a core process on the affected servers that became overloaded and unresponsive, resulting in severe capacity loss. By 6:00 p.m., according to a Microsoft status page update at 5:11 p.m.
File-sharing platforms and cybersecurity utilities running on the Microsoft ecosystem experienced intermittent failures, alongside other company products such as Teams and the AI assistant Copilot, plus services like SharePoint and OneDrive.
OpenAI reported investigating connection issues tied to Microsoft infrastructure that caused new connections to drop. Anthropic similarly identified upstream supplier troubles impacting its Microsoft 365 integrations, MarketScreener Nederland reported.
Downdetector figures showed total incident reports falling to roughly 34,490 by evening. At 5:47 p.m. ET, the number of reports for Microsoft 365 issues had dropped to nearly 13,000 according to Downdetector, while 763 users reported issues accessing Teams. Microsoft shares remained largely stable despite the widespread platform failure.
“As capacity is restored, customers may experience gradual recovery as their clients reconnect,” Microsoft said on Nov. 12, 2026.
Earlier coverage: Global Microsoft Outage Disrupts Teams, Outlook, and Microsoft 365 Services
