Microsoft 365 outage disrupts Outlook, Teams and Copilot worldwide
Microsoft says an overwhelmed server process caused the disruption; partial recovery has been reported, but services have not returned to normal everywhere
Microsoft is working to restore a widespread global outage that disrupted Outlook email and several other Microsoft 365 services for users, businesses, governments and public organizations.
The incident began on November 12 and continued into November 13. The most visible problem was the loss of access to Outlook and Exchange Online mailboxes. Many users were unable to open their inboxes, send messages or receive new email. Parts of Microsoft Teams, Copilot, SharePoint Online and several security and productivity services were also affected.
Microsoft has reported early signs of stabilization and partial recovery in some regions, but the company has warned that service capacity has not yet returned to normal everywhere. Administrators should continue to monitor the Microsoft 365 Service Health page for tenant-specific updates.
What happened?
Microsoft initially reported problems connecting to Exchange Online, the cloud service that stores and delivers email for many Outlook users. The problem was first identified in the Americas, but reports soon spread to other regions.
According to Microsoft’s explanation, a process on affected servers that helps establish secure connections became overwhelmed. Those servers then stopped processing requests, reducing available capacity and causing connection failures for users.
Microsoft has not described the incident as the result of a confirmed software release or a single final root cause. The company has been investigating why the process became overwhelmed and why automated server health checks removed some infrastructure from service.
Some servers reportedly went offline after failing automated health checks. Microsoft also said heavier-than-usual load across parts of its infrastructure contributed to connection problems. The final technical explanation may change as the company completes its investigation.
Which Microsoft services were affected?
Outlook and Exchange Online
Email was the main service affected. Users reported that Outlook would not load, messages could not be sent or received, and Exchange Online mailboxes were inaccessible or extremely slow.
Microsoft later extended its email timeout window to 48 hours. The measure was intended to help protect delayed messages while service recovery continued.
Microsoft Teams
Teams was also affected, particularly features connected to Outlook and users’ calendars. Scheduled meetings and calendar-based functions could fail even when basic chat or direct meeting access remained available for some users.
Microsoft Copilot
Some users could not load Copilot conversations or receive responses. Copilot features that depend on access to email, files and calendars were also affected.
SharePoint and productivity tools
The incident could affect SharePoint Online, Planner, To Do and Intune. Organizations using these services may have experienced problems accessing files, coordinating work or managing devices.
Security services
Several Microsoft security services were included in the reported impact, including Defender XDR and Defender for Office 365. The extent of the effect varied by service, region and customer environment.
Basic functions in Word, Excel and PowerPoint generally continued to work, but cloud-dependent features such as SharePoint sharing, cloud printing and access to recently used files could be affected.
How widespread was the outage?
The disruption became global within hours. Downdetector recorded outage reports in 74 countries and territories in about one hour. At one point, nearly 130,000 reports related to Outlook problems appeared on the service.
The outage disrupted organizations in several sectors. Governments, courts, banks, transport operators, schools and businesses reported difficulties using Microsoft email and collaboration tools.
In the United States, the House of Representatives said its engineers were working with Microsoft. Several city governments reported that staff could not send or receive email, while emergency services remained active.
In the United Kingdom, disruption to NHS email systems was expected to affect some communications involving prescriptions. Rail operators in Canada, Germany and the United Kingdom warned that customers might not receive email updates or tickets, although the outage did not necessarily stop train operations.
Courts and government services in parts of Asia also reported delays. Some organizations created temporary workarounds, including phone contact, SMS notifications and physical copies of documents.
The outage also affected private companies. At least one company postponed an earnings call because of business disruptions caused by the Microsoft outage.
Is this a cyberattack?
Microsoft has said there is currently no indication that the outage was caused by malicious activity or a cyberattack.
The statement does not mean Microsoft has completed its investigation. It means the company has not found evidence linking the incident to a cyberattack based on the information available in its current updates.
The reported failure pattern is consistent with an infrastructure and capacity incident: servers became unavailable or stopped processing requests, while Microsoft worked to restart affected infrastructure and redirect traffic. The company is still investigating the underlying reason for the server failure.
How is Microsoft responding?
Microsoft has described several recovery actions:
•Restarting and validating affected servers.
•Returning stable infrastructure to service gradually.
•Rerouting traffic to alternate paths where possible.
•Increasing capacity to address traffic imbalances.
•Monitoring changes before expanding them across more infrastructure.
•Extending the email timeout window to protect delayed messages.
Some early fixes did not produce sustained recovery, so Microsoft shifted to multiple recovery workstreams. The company said it was seeing early stabilization and capacity improvements, while warning that recovery remained incomplete.
Users in some regions reported that Outlook and other services began working again, but access was not restored consistently for every customer or tenant.
What should Microsoft 365 users do?
Individual users should check the Microsoft 365 Service Health page or their organization’s internal status updates. If the issue is already listed as an active Microsoft incident, repeatedly changing local settings or reinstalling applications is unlikely to solve the problem.
Organizations should:
1.Check the Microsoft 365 admin center under Health and Service health for tenant-specific updates.
2.Record the incident number and the time the disruption began.
3.Use phone, SMS or alternative communication channels for urgent messages.
4.Avoid broad tenant, DNS, identity or client-configuration changes while the incident remains active.
5.Check delayed and failed messages after service recovery.
6.Review the Microsoft 365 issue history after the incident for a final update or post-incident report.
Users who need access to tickets, appointments or official messages should check the relevant website or mobile app, and contact the organization by phone if an email is unavailable.
What happens next?
Microsoft is expected to continue posting updates as capacity is restored and affected servers are returned to service. A complete post-incident explanation may provide more detail about why the secure-connection process became overwhelmed, why health checks removed servers from service, and what safeguards will be added to prevent a similar failure.
For now, the key distinction is between partial recovery and full restoration. Some users may regain access while other regions, tenants or dependent services continue to experience delays.
The latest status information is available through the Microsoft 365 Service Health page. The public Azure status page currently shows no active Azure events, indicating that this incident is primarily associated with Microsoft 365 and related online services rather than a general Azure regional outage.
Editor’s note
Update this article with a new timestamp whenever Microsoft publishes a material status change. Continue to attribute the technical cause to Microsoft until the company publishes a final post-incident report.
Visual note: accompanying images are illustrative technology visuals and contain no logos or official screenshots.
