REDMOND, Washington — Microsoft is still working to restore several Microsoft 365 services after a widespread disruption left users struggling to access Exchange Online mailboxes, Outlook and parts of Microsoft Teams, with the outage extending into a second day on Friday, November 13.
The incident began on Thursday, November 12, and has affected access to mailboxes through Outlook on the web, Outlook desktop and mobile connections. Microsoft has also identified disruption across other services that depend on Exchange Online, including Teams calendar functions, Copilot, SharePoint-connected features and several security and administration tools.
In its latest service-health update reviewed on Friday morning, Microsoft said recovery actions were progressing in phases and that global telemetry and customer reports showed incremental improvement in several workloads. However, service capacity had not returned to normal and performance remained variable as traffic was gradually reintroduced. The incident remained listed as an active service degradation.
Exchange Online Remains At The Centre Of The Disruption
Microsoft’s incident notice says users may be unable to connect to Exchange Online through several methods, including Outlook on the web, Messaging Application Programming Interface (MAPI), Exchange ActiveSync and REST-based connections. Email delivery may also be delayed, affecting both individual users and organisations that rely on Microsoft-hosted mail systems.
The company’s incident reference, MO1550821, describes a wider Microsoft 365 problem linked to services that interact with Exchange Online. Microsoft said it was prioritising mail queues and backlog processing and had extended the email timeout window to 48 hours to help preserve delayed messages while recovery continues.
That measure is intended to protect messages caught in delivery queues rather than guarantee that every mailbox will immediately become accessible. Users may therefore continue to experience delayed delivery, intermittent access or repeated connection attempts as infrastructure is restored.
Teams Is Partially Affected — But Core Calls And Messages Continue
Microsoft Teams is also experiencing problems, although the company’s status notice makes an important distinction: most core functions, including joining calls and meetings, participating in group chats and sending channel messages, are not broadly affected.
Disruptions are concentrated in features that depend on Exchange Online. These include calendar viewing and scheduling, sending or editing meeting invitations, creating Live or Virtual events, and some Copilot responses that rely on Outlook, calendar or Microsoft 365 files. Users may also encounter problems adding contacts, syncing contact information, navigating app chats and creating or deleting private and shared channels. Standard channels were reported as working.
The distinction matters for organisations trying to keep operations running. Teams users may still be able to hold meetings and exchange messages even while scheduling, calendar integration and other connected tools fail. Microsoft’s guidance indicates that the impact varies by feature rather than making the entire collaboration platform unavailable.
Why The Outage Has Been Difficult To Resolve
Microsoft’s investigation found that a large number of servers had become unexpectedly unavailable, shifting additional demand onto the infrastructure that remained online. The company later described problems involving server stability, traffic management and a process on affected servers responsible for establishing secure connections.
Engineers have been restarting affected infrastructure, adjusting network and routing configurations, redistributing traffic and applying patches intended to improve server stability. Microsoft has also been expanding capacity through virtual machines and carefully returning infrastructure to service in stages.
Some early recovery efforts produced improvements, but Microsoft reported that certain changes did not deliver the expected results and that servers could become unresponsive again after receiving traffic. The company’s more recent updates describe improved stability after an upstream authentication and routing configuration patch, which it is expanding to additional infrastructure.
Microsoft said it had no evidence that malicious activity caused the incident. It has promised to publish a post-incident report explaining the root cause and the measures it plans to take to reduce the risk of a similar disruption after recovery is complete.
Outage Spreads Beyond Email And Meetings
The disruption has extended beyond the services most users notice first. Microsoft’s incident notice lists possible impacts to Microsoft 365 Copilot, SharePoint Online, Microsoft Defender, Purview, Planner, To Do, Intune, Power Apps, Power BI and other connected workloads. The exact effects differ by product and by whether a feature depends on Exchange Online or related Microsoft Graph services.
The Associated Press reported that the outage affected companies and government operations in multiple countries, with users across Asia and the United States reporting problems. More than 130,000 users had reported Outlook access problems to Downdetector at the Thursday peak, although reports later declined. Some public services and businesses also reported disruptions to email-dependent work.
The incident illustrates how a fault in a widely used cloud service can spread through connected workplace products. A mailbox outage can affect more than sending and receiving messages when calendars, identity workflows, document sharing, security controls and AI assistants depend on the same underlying platform components.
What Users And Organisations Can Do While Recovery Continues
Users experiencing problems should check the Microsoft 365 service status page or their organisation’s Microsoft 365 admin communications for updates. Repeatedly changing account settings or deleting mail profiles is unlikely to resolve an infrastructure-side incident and could make troubleshooting more difficult.
Where business continuity plans permit, organisations can use approved alternative communication channels for urgent coordination, while keeping sensitive information within authorised systems. Administrators should monitor mail queues, delivery reports and service-health notices, and avoid making unnecessary tenant configuration changes during the recovery period.
Users should also be cautious about unsolicited messages claiming to offer outage fixes or account recovery links. Microsoft has not attributed the disruption to a cyberattack, and the company’s published updates direct customers to its official service-health channels.
A Reminder Of Cloud-Service Dependence
For companies, schools, public agencies and other organisations that use Microsoft 365 as a central communications platform, the incident is a reminder that cloud availability is an operational risk as well as a technology issue. Email, meetings, file access and security processes can be closely connected, meaning a disruption in one part of the system can affect many daily activities.
Microsoft’s recovery work is continuing, and the company has not declared the wider incident resolved. Although some services and regions are showing improvement, users should expect intermittent problems until capacity and service health return to normal. The next updates from Microsoft will be important in establishing whether the staged repairs are producing sustained recovery.
Reporting is based on Microsoft service-health updates reviewed on November 13, 2026, and reporting by the Associated Press.