New Delhi: Microsoft is expanding corrective measures to resolve a global outage affecting Outlook and several Microsoft 365 services, after users experienced disruptions for more than seven hours. The company has reported encouraging results from server restarts but is continuing to monitor infrastructure stability before restoring normal traffic levels.

The disruption began on November 12 and affected Microsoft’s Exchange Online email platform, along with several applications and features that depend on it. Users reported difficulties accessing their mailboxes, sending and receiving emails, loading Microsoft 365 applications and using certain workplace tools.

In an update published on November 13, Microsoft said its investigation had identified an overloaded process responsible for establishing secure connections on affected servers. The process was causing some servers to stop processing requests, resulting in connectivity failures across multiple regions.

The company is now testing configuration changes, restarting affected infrastructure and restricting certain types of traffic in specific locations as it works to restore services.

Microsoft identifies overloaded secure-connection process

Microsoft’s investigation found that a process on affected servers responsible for establishing secure connections was becoming overwhelmed. As a result, the servers were unable to process incoming requests reliably.

The company is preparing a configuration change designed to address the behaviour across all affected servers. Rather than deploying it everywhere immediately, Microsoft is first validating the change on a smaller group of servers before expanding its application.

The company is also restarting affected infrastructure and monitoring whether the servers remain stable once they begin handling traffic again.

Another part of the investigation concerns a recent network configuration change that coincided with the beginning of the disruption. Microsoft has started reverting that change and is examining whether doing so helps restore normal operations.

The company has also introduced temporary traffic restrictions in selected locations. These measures are intended to reduce the load on affected infrastructure while Microsoft checks whether the servers can handle a narrower range of incoming connections.

Microsoft said it would gradually reintroduce additional traffic after confirming that the servers remained stable.

Outlook and Exchange Online users face email disruptions

Outlook has been among the most visibly affected services. Users may be unable to access their mailboxes through Outlook on the web, the desktop application, Exchange ActiveSync or REST-based connections.

Email delivery may also be delayed, meaning that messages could take longer than usual to reach recipients. The disruption has affected access to Exchange Online, Microsoft’s cloud-based email and calendaring platform.

The incident has also affected some Microsoft 365 administrative functions. Administrators may find that certain pages in the Microsoft 365 admin centre fail to load, while users may be unable to view recently accessed files in Microsoft 365 applications.

The impact has extended beyond email because several Microsoft services rely on Exchange Online to provide particular features. However, Microsoft clarified that components that do not depend on Exchange Online continue to function.

Microsoft Teams, Copilot and other services affected

Microsoft Teams users may encounter problems with features that depend on Exchange Online, including calendars and meeting scheduling. Some organisations may also experience failures when creating chats in environments using Information Barriers.

However, Microsoft said core messaging and online meetings remained largely functional. This distinction means that not every Teams feature was necessarily unavailable during the incident.

Microsoft Copilot Chat has also been affected. Users may be unable to load the service or receive responses through its web and desktop applications. Copilot experiences that require access to workplace information, such as emails, calendars and files, may also fail.

Other affected services and features include:

  • Microsoft Planner: Users may experience unreliable plan and task operations.
  • Microsoft To Do: The application may fail to load or complete certain operations.
  • Microsoft Purview: Several functions, including data classification, automatic labelling and Data Loss Prevention, may be disrupted.
  • Microsoft Defender: Some Defender portal pages and solution tabs may not load, while Safe Links verification may be affected.
  • Microsoft Graph: API requests involving Exchange Online information, including emails, calendars and contacts, may time out.
  • Power BI: Some users may face problems exporting reports carrying sensitivity labels.
  • Universal Print: Users may encounter errors when submitting print jobs or accessing administrative features.
  • Windows 365: Certain Cloud PC connections configured to use Microsoft Purview Customer Key may be affected.

Microsoft also reported that access to files stored directly in SharePoint Online remained functional, although features dependent on Exchange Online could be disrupted.

Downdetector reports show scale of disruption

The outage generated a significant number of complaints from users across different regions. Downdetector, which tracks user-submitted reports of service problems, recorded a sharp increase in reports involving Outlook and other Microsoft platforms.

That Outlook-related complaints on Downdetector peaked at approximately 1.38 lakh around 1 pm Eastern Time on November 12. Reports subsequently declined, although users continued to experience problems.

These figures represent reports submitted to the outage-monitoring platform and should not be treated as a confirmed count of affected customers.

The disruption also affected businesses that depend on Microsoft’s cloud services. That electric truck maker Workhorse Group postponed its third-quarter results announcement from November 12 to November 16, citing the global Microsoft outage.

The incident also affected third-party services that connect to Microsoft 365. OpenAI said new connections to its Microsoft connectors could fail and that some tools might not work as expected. Anthropic also traced problems with its Microsoft 365 connector to an upstream provider.

Microsoft reports positive results but recovery remains gradual

In its November 13 update, Microsoft said it was seeing positive results from efforts to restart affected infrastructure. However, the company was still monitoring server performance to confirm that the systems could remain stable under normal traffic conditions.

The cautious recovery process reflects a problem encountered during earlier restoration attempts. Servers that had initially been returned to service were observed becoming unresponsive again once they started receiving traffic.

Microsoft is therefore combining server restarts with configuration changes, traffic restrictions and the reversal of a recent network change. These measures are intended to restore capacity without triggering further instability.

The company has not announced a confirmed end to the incident in the update covered by this report. Users may consequently continue to experience intermittent problems until the affected infrastructure is stable and normal traffic can be restored.

The outage highlights the dependence of businesses and organisations on cloud-based productivity platforms. A disruption to a central service such as Exchange Online can affect several connected applications, even when their underlying systems are otherwise operating normally.