Overview

A widespread Microsoft 365 outage has disrupted access to several of Microsoft's cloud-based services, leaving users and businesses across multiple regions unable to reliably access Outlook, Microsoft Teams, Copilot and other workplace applications. The disruption, which began on November 12, 2026, affected email communications, calendar access and various enterprise productivity features, triggering a surge in outage reports worldwide.

The incident primarily affected Exchange Online, Microsoft's cloud-based email and calendar infrastructure, which supports Outlook and several interconnected Microsoft 365 applications. Users reported difficulties loading inboxes, sending and receiving emails, accessing calendars and connecting to workplace services.

The disruption extended beyond the United States, with users in the United Kingdom, India, Japan, Australia and other regions reporting connectivity problems. Microsoft acknowledged the widespread impact and began investigating unexpected server failures that placed additional pressure on its remaining infrastructure.

While the company initiated multiple recovery measures, including restarting affected servers and investigating configuration changes, service restoration remained gradual. Microsoft has not identified a confirmed root cause, and its initial investigation has not indicated that the outage was caused by a cyberattack.

Microsoft 365 Services Affected by the Outage

The outage affected multiple services within Microsoft's productivity ecosystem, particularly those dependent on Exchange Online. Although not every feature across these applications became unavailable, users experienced disruptions to essential communication and collaboration functions.

The major affected services included:

• Microsoft Outlook: Users experienced difficulties accessing inboxes, loading emails, and sending or receiving messages across web, desktop and mobile clients.

• Microsoft Exchange Online: The underlying email infrastructure experienced connectivity problems, affecting mailbox access and calendar functionality.

• Microsoft Teams: Some users encountered disruptions involving calendars, meeting scheduling and other features connected to Exchange Online.

• Microsoft 365 Copilot: Users reported difficulties accessing AI-powered workplace assistance and information connected to Microsoft 365.

• SharePoint Online: Certain features dependent on Microsoft 365 connectivity experienced disruptions.

• Microsoft Defender XDR: Some security-related service capabilities were also affected.

• Planner and To Do: Users experienced issues with certain productivity and task-management functions.

The incident also affected third-party applications relying on Microsoft 365 integrations, highlighting how disruptions to a central cloud service can extend into interconnected business platforms.

Key Facts of the Incident

What Happened During the Microsoft 365 Outage?

The disruption began on November 12, when Microsoft started receiving reports of users experiencing difficulties connecting to Exchange Online mailboxes. Initially, the company identified connectivity problems affecting users in the Americas. However, subsequent updates indicated that the issue could affect Microsoft 365 connectivity across different regions.

As the incident developed, users reported problems accessing their Outlook inboxes, sending and receiving emails, and retrieving calendar information. Several other Microsoft applications also experienced disruptions because of their reliance on shared cloud infrastructure and Exchange Online services.

The outage quickly became a major concern for businesses that depend on Microsoft 365 for daily operations. Employees faced difficulties communicating with colleagues, accessing workplace information and coordinating meetings.

Outage-tracking data showed that reports of Outlook problems reached nearly 130,000 at their peak. Microsoft 365 also recorded more than 47,000 reports, while Teams and Copilot experienced thousands of additional complaints. Reports emerged from more than 70 countries and territories.

The disruption also affected certain government operations and organisations relying on Microsoft's cloud infrastructure, demonstrating the broader consequences of a failure within widely used enterprise technology services.

What Caused the Microsoft 365 Outage?

Microsoft's initial investigation pointed towards unexpected server failures rather than an unusual increase in user traffic.

The company identified several servers that had become unavailable after failing automated health checks. As these servers stopped processing requests, the remaining infrastructure had to handle additional workloads, resulting in increased pressure and connectivity failures.

Microsoft also identified an issue involving a core process responsible for establishing secure connections. The process became overwhelmed on affected servers, preventing them from handling incoming requests effectively.

The company initiated several recovery measures, including:

• Restarting affected servers: Microsoft attempted to bring unavailable servers back online to restore infrastructure capacity.

• Redirecting network traffic: Traffic was rerouted through alternative infrastructure to reduce pressure on affected systems.

• Testing alternative health checks: Microsoft experimented with a different server health-check method to identify and recover affected systems.

• Investigating configuration changes: The company examined recent network configuration updates and began rolling back a change that coincided with the beginning of the disruption.

• Restricting certain traffic: Some traffic reaching recovering servers was limited to prevent them from becoming unresponsive again.

Despite these efforts, recovery proved challenging because some servers that initially returned to service became unstable once they started receiving traffic.

Microsoft has not established a definitive root cause for the incident. Its initial investigation also found no indication that the disruption was caused by a cyberattack.

Timeline of the Microsoft 365 Outage

The disruption developed over several hours, beginning with Exchange Online connectivity problems before expanding into a wider Microsoft 365 service incident.

Is Microsoft Outlook and Microsoft 365 Working Again?

As of November 13, 2026, Microsoft had begun restoring affected infrastructure, and outage reports had declined from their peak. However, the recovery was not uniform, with some users continuing to experience connectivity and mailbox access problems.

Microsoft's service health information continued to indicate service degradation for Microsoft 365 business and enterprise customers in its November 13 update. Its consumer service dashboard displayed a different operational status, highlighting that service availability could vary between products and customer environments.

The company had not provided a definitive timeline for complete restoration in the updates available at the time.

Organisations using Microsoft 365 were advised to monitor the official service health dashboard and the Microsoft 365 admin centre for updates relating to the incidents.

The disruption was tracked under two incident references:

• EX1550543: Exchange Online mailbox connectivity issues.

• MO1550821: Broader Microsoft 365 service disruption.

What Organizations Should Do During Major Cloud Service Outages

The Microsoft 365 disruption highlights the importance of having business continuity plans for cloud-dependent operations. Organisations that rely heavily on a single productivity ecosystem can face significant operational challenges when its underlying infrastructure becomes unavailable.

Businesses should consider the following measures to improve resilience:

1. Establish Alternative Communication Channels

Organisations should maintain backup communication methods for employees, including alternative messaging platforms and emergency contact procedures. This helps teams coordinate critical activities when corporate email and collaboration services become unavailable.

2. Implement Business Continuity Plans

IT teams should develop and regularly test business continuity and disaster recovery procedures. These plans should identify critical applications, alternative workflows and responsibilities during prolonged service disruptions.

3. Monitor Cloud Service Health

Organisations should continuously monitor the availability of essential cloud services and establish internal processes for responding to service degradation. IT administrators should also maintain visibility into vendor incident notifications.

4. Maintain Data Backup and Recovery Procedures

Businesses should ensure that critical information is protected through appropriate backup and recovery mechanisms. Depending on the application and configuration, organisations should evaluate independent recovery options rather than relying entirely on the availability of a single cloud platform.

5. Prepare Employees for Unexpected Disruptions

Employees should understand how to respond when essential workplace applications become unavailable. Clear communication procedures can reduce confusion, prevent operational delays and help employees identify alternative ways to complete critical tasks.

Why This Microsoft 365 Outage Matters

The incident highlights how dependent modern businesses have become on centralised cloud infrastructure. Microsoft 365 supports essential business functions, including email communication, document management, scheduling, collaboration and security operations.

When a critical component such as Exchange Online experiences a major disruption, the impact can extend across multiple applications and organisations that depend on the same infrastructure.

The outage also raises important questions about cloud resilience, infrastructure redundancy and the ability of businesses to maintain operations during prolonged service interruptions.

Another concern is the potential for cybercriminals to exploit the confusion surrounding major service outages. Attackers may use fake Microsoft service notifications, technical support messages and account recovery requests to trick employees into revealing login credentials or approving malicious authentication requests.

Organisations should therefore remind employees to verify service-related communications and avoid clicking suspicious links or sharing authentication information in response to unexpected outage notifications.

Ultimately, the incident demonstrates that business continuity requires more than relying on cloud service availability. Organisations must also prepare employees, establish alternative communication channels and strengthen their overall cybersecurity awareness.