When email, meetings and workplace collaboration tools fail together, the disruption can spread through an organization far beyond its IT department. A major Microsoft 365 outage that began on November 12, 2026 and continued into November 13 affected services including Outlook, Teams and Copilot, interrupting communications for businesses, government agencies and other organizations around the world.

Microsoft attributed the incident to server and infrastructure problems and said it was not aware of malicious activity. Reuters reported that the outage lasted more than 24 hours and that Microsoft’s broader deployment of fixes was stabilizing services, although a complete recovery timeline remained uncertain. The company’s statements did not support describing the outage as a cyberattack.

Which Microsoft 365 services were affected?

Outlook was among the most visible problems because it is central to email and calendar workflows. Users reported trouble accessing mailboxes, sending or receiving messages and connecting through different methods. Teams and Copilot were also affected, while the impact varied across services and users.

Reuters reported that Microsoft’s service notices pointed to Exchange Online dependencies. Exchange Online provides cloud-hosted email, calendars, contacts and related functions. When a shared service becomes unavailable or overloaded, applications that depend on it can experience problems even if their own interfaces are still reachable.

The disruption also affected organizations that rely on Microsoft services behind the scenes. Reuters described interruptions involving government agencies, financial firms, airlines and companies using Microsoft 365 connectors. That illustrates a key feature of cloud computing: a service outage can affect not only the company’s direct customers but also other products and workflows connected to the same infrastructure.

What Microsoft said caused the outage

Microsoft said server issues were responsible and that it was not aware of malicious activity. Reuters reported that the company had been moving traffic away from affected infrastructure, restarting servers and applying fixes. Some restarted servers reportedly struggled again when traffic returned, complicating recovery.

That is different from evidence of a breach. A service becoming unavailable does not, by itself, establish that attackers accessed customer data or compromised accounts. Microsoft’s public explanation pointed to infrastructure and server problems, not a confirmed security incident. Organizations should still follow their normal security procedures, but should not circulate unverified claims that the outage exposed private email or files.

What users should do when Outlook or Teams stops working

During an outage, repeatedly changing passwords or reinstalling applications is unlikely to fix a problem affecting Microsoft’s cloud infrastructure. It can also create unnecessary support work. A more useful response is to verify the service status, preserve urgent work and use approved alternatives.

• Check Microsoft’s service health: Microsoft 365 administrators can review the Service health page in the admin center for incident updates affecting their tenant.
• Confirm the scope: Check whether the problem affects one device, one account, one organization or multiple Microsoft services. This helps separate a local connectivity issue from a wider outage.
• Use approved backup channels: For urgent communication, follow your organization’s continuity plan, such as a designated phone bridge or alternate messaging platform.
• Protect unsent work: Save drafts and local copies where possible. Do not assume a message or document has synchronized until the service confirms it.
• Avoid risky workarounds: Do not send confidential business information through personal email or unapproved consumer apps simply because a corporate tool is unavailable.

Employees should follow their organization’s instructions rather than independently moving company files to personal accounts. For administrators, clear internal status updates can reduce duplicate support requests and prevent employees from improvising unsafe workarounds.

How businesses can reduce the impact of the next outage

No cloud provider can promise that every service will be available every minute. Organizations can, however, plan for the possibility that a provider or a critical dependency will fail. The most useful continuity plan identifies which workflows must continue, who makes decisions during an outage and which approved alternatives are available.

Businesses should test backup communication channels before they are needed. They should also identify critical records that need offline access, document escalation contacts outside the affected platform and establish a process for reconciling work created during downtime. A backup tool that employees have never used is not much of a backup.

Vendor concentration is another issue. A company that uses one provider for email, identity, file storage, meetings and automation may gain convenience and easier administration, but it can also create a shared point of failure. Diversifying every tool is not always practical; understanding the dependencies and planning for them is.

What the outage means for Microsoft 365 customers

The November incident was a reminder that widely used cloud platforms remain dependent on complex infrastructure. Microsoft said it was applying fixes and seeing signs of stabilization, but users should distinguish that update from a guarantee that every mailbox, tenant and connected application has fully recovered.

For customers, the practical response is to monitor Microsoft’s service-health notices, follow internal continuity procedures and avoid treating unverified outage rumors as confirmed security findings. For organizations, the longer-term lesson is to test how essential work continues when a provider’s core services are unavailable.

Related reading: How to Organize Your Digital Life; How to Read a Tech Review.

Sources and further information: Reuters: Microsoft outage hits Outlook, Teams and Copilot worldwide; Microsoft 365; Microsoft 365 service health and status.