Microsoft 365 Outage Lasts Nearly 10 Hours, Affecting Outlook, Defender, and Purview

A major Microsoft 365 outage struck North American users late on January 22, 2026, dragging on for nearly 10 hours and causing widespread disruption to critical business services. The incident, which began around 19:37 UTC, primarily affected Microsoft Outlook, but also impacted Microsoft Defender and Purview services, leaving many organizations without email communication and security monitoring capabilities.

Microsoft officially acknowledged the problem on its Microsoft 365 service health dashboard, stating that "a portion of service infrastructure in North America is not processing traffic as expected." The company's initial communication indicated that users might experience issues with email flow, connectivity, and authentication. For many businesses, particularly financial services firms, the impact was severe. One user reported, "You got to be kidding me! We haven't gotten emails since 1:30 pm and we run a financial company with clients!!"

The outage manifested in different ways across affected tenants. Internal mail flow slowed significantly, while external email delivery stopped altogether for many organizations. Users attempting to access Outlook via web and desktop clients encountered connectivity issues, and the Purview compliance portal became inaccessible. Microsoft Defender, the company's security platform, also experienced downtime, leaving security teams without visibility into potential threats during the outage period.

Downdetector, a real-time outage tracking service, recorded over 15,000 reports at the peak of the incident. The geographic concentration of reports aligned with Microsoft's acknowledgment of a North American infrastructure issue. The prolonged nature of the outage suggested a complex problem within Microsoft's cloud infrastructure, rather than a simple configuration error or localized failure.

Microsoft's recovery process was notably slow, with the company working for hours to restore service and balance traffic across its environment. The infrastructure "lurched back into life" gradually, according to user reports, rather than recovering all at once. By 05:33 UTC on January 23, nearly ten hours after the initial acknowledgment, Microsoft reported that it had "restored access to the affected services and mail flow remains stable." The company followed up approximately an hour later, stating it had "confirmed that impact has been resolved."

However, user reports suggested that recovery was not uniform. Some users continued to report issues even after Microsoft's resolution announcement, with one posting, "No it has not been resolved," and another stating, "Our tenant is still unable to receive external email. I do not think this is resolved." This discrepancy highlights a common challenge in large-scale cloud outages: partial recovery where some services return while others remain affected, or where recovery is inconsistent across different tenants or regions.

This incident is part of a troubling pattern for Microsoft's cloud services in early 2026. The company has already experienced multiple disruptions this year, including an Azure outage in Western Europe that Microsoft blamed on a "thermal event," and a major AWS outage across the US-East region that affected numerous internet services. The frequency of these outages raises questions about cloud infrastructure resilience and the concentration risk inherent in major cloud platforms.

For IT administrators and compliance officers, this outage serves as a critical reminder of the importance of business continuity planning and multi-cloud or hybrid strategies. Organizations relying solely on Microsoft 365 for email and collaboration found themselves completely offline for nearly a full business day. Financial services, healthcare, and other regulated industries face additional compliance challenges when such outages occur, as they may impact data availability requirements under regulations like GDPR, HIPAA, or financial industry standards.

The incident also underscores the importance of clear communication from cloud providers during outages. While Microsoft provided updates through its service health dashboard, many users reported difficulty accessing this information during the outage itself. Organizations should establish multiple communication channels for service status updates, including direct vendor contacts and third-party monitoring services.

From a technical perspective, the outage appears to have stemmed from infrastructure-level issues rather than application-level bugs. Microsoft's description of "a portion of service infrastructure" not processing traffic suggests potential problems with load balancing, network routing, or compute resource allocation within its North American data centers. The company has not yet provided specific technical details about the root cause or the steps taken to prevent recurrence.

The financial impact of such outages can be substantial. For large enterprises, even a few hours of email downtime can result in millions of dollars in lost productivity and potential business opportunities. For regulated industries, there may also be reporting requirements or regulatory scrutiny following extended service disruptions.

Microsoft has not yet responded to requests for additional details about the cause of the outage or the specific measures being implemented to prevent similar incidents. The company typically conducts post-incident reviews for major outages and publishes detailed reports through its Microsoft Azure status page and Office 365 service health portals. These reports often include technical details about the failure chain and the remediation steps taken.

For organizations affected by this outage, immediate steps should include verifying that all email queues have cleared and that external mail flow has fully normalized. Security teams should review any potential security gaps that may have occurred during the Defender outage period. Compliance officers should document the incident for any required regulatory reporting and review business continuity plans to identify potential improvements.

The incident also highlights the value of having backup communication channels. Organizations that maintained alternative email systems or collaboration tools were able to maintain some level of business continuity during the outage. Similarly, organizations with on-premises email infrastructure or hybrid deployments experienced less impact than those fully dependent on cloud services.

As cloud services become increasingly critical to business operations, the frequency and impact of outages will continue to be a major concern for IT leaders and compliance professionals. This Microsoft 365 outage serves as a stark reminder that even the largest cloud providers are not immune to infrastructure failures, and that comprehensive risk management strategies must account for the possibility of extended service disruptions.