People in any region may be unable to reach Outlook and other Microsoft 365 services after a large number of servers became unexpectedly unavailable, Microsoft 365 Status says. The company is still working to restore capacity. In its latest updates, it says servers it has returned to service can become unresponsive again once they begin receiving traffic, and it hasn’t given a time for full recovery.
We’re investigating reports of users experiencing issues accessing Exchange Online mailboxes through multiple connection methods in the Americas. More details can be found in the Microsoft 365 admin center under EX1550543.
November 12, 2026
Microsoft 365 Status first reported problems accessing Exchange Online mailboxes through multiple connection methods in the Americas. A follow-up shortly afterwards confirmed the issue may affect Microsoft 365 service connectivity for users in any region.
The Exchange Online incident, EX1550543, covers mailbox access through Outlook on the web, the Messaging API (MAPI), Exchange ActiveSync and the REST API. A related Microsoft 365 suite incident, MO1550821, lists Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR as potentially affected. A later admin center update also added Microsoft Planner and Microsoft To Do. Microsoft’s public status page has since added Microsoft Intune, Microsoft Defender for Office 365, Microsoft Purview (including authorization, auto labelling, data loss prevention, communication compliance and data classification), Universal Print, the Microsoft 365 Apps admin centre, Power BI exports of reports with sensitivity labels to PDF, and Windows 365 Cloud PCs that use Microsoft Purview Customer Key. Both incidents are still listed as service degradations, with no end time, in Microsoft’s latest updates. The status page also records service degradation for Microsoft consumer products, and still says no Azure issues have been detected.
RNZ, citing Downdetector, said there were more than 130,000 reports of people having trouble with Outlook early on Friday. Other outlets put the peak around the same figure. Downdetector collates status reports from a number of sources, and RNZ noted that the actual number of affected users may vary. Reuters separately counted more than 97,000 Outlook reports, more than 38,000 for Microsoft 365 and about 4,500 for Teams at one point on Thursday afternoon in the United States. Some Downdetector tallies also included reports about Azure, OneDrive and the Microsoft Store. Microsoft’s public status page said no Azure issues were detected.
Microsoft 365 issues are cutting people off from their email right now.
November 12, 2026
Microsoft first described elevated load across multiple regions. It later said: “We’ve determined that the elevated load isn’t driven by an overall increase in traffic, but by a large number of servers being unexpectedly unavailable, which is shifting load onto the remaining infrastructure.”
In subsequent updates, the company said affected servers were failing automated health checks and dropping out of service. It hasn’t identified a recent change that correlates with the start of the impact, but it says the failed checks may originate from a specific component that processes server health. It’s testing a configuration change to bypass that component on a subset of servers, and it has taken steps to prevent more servers from being taken out of service. It’s also investigating why the affected servers are seeing elevated processor usage.
We’re testing a configuration change to address a problem that’s causing servers to fail automated health checks and become unavailable. In parallel, we’ve initiated a restart of all affected servers and are monitoring health as they return to service. More info under EX1550543
November 12, 2026
To reduce the strain, Microsoft says it has paused all deployments and configuration changes, redistributed Outlook connection traffic across its worldwide infrastructure, and is moving more traffic off the affected systems. It has also started restarting affected servers and is watching them as they return. It warned that redistributing traffic may result in some latency while that change is in effect.
Microsoft later said an alternative service health check method had let a subset of affected servers return to service, and that it was applying that change more broadly. It also said it was assessing whether reverting a small number of recent configuration updates it had identified could help accelerate recovery.
In a further update, it said its actions so far hadn’t provided the anticipated relief, and that a core process on affected servers was becoming overwhelmed, causing capacity loss. It said it was isolating a portion of the infrastructure, restarting affected components, and reintroducing traffic to check that services stayed stable before applying the change more broadly.
It later said it was returning a portion of the affected servers to service and had seen limited recovery, with users likely to see a gradual return as their clients reconnect. In its latest public update, Microsoft says those servers can become unresponsive again once they begin receiving traffic. It’s analysing diagnostic data with its networking and platform experts, temporarily limiting which types of traffic can reach the affected infrastructure in some locations, and rebuilding a subset of affected servers using a previous software configuration.
In a further update, Microsoft 365 Status said it had reviewed known impact scenarios and revised the list of impacted services and features. It pointed people to the more-info section of MO1550821 in the Microsoft 365 admin center, and to its public status page if the admin center isn’t available. It said it was continuing work to isolate the issue affecting server availability, as well as other workstreams.
We’ve reviewed known impact scenarios and revised the list of impacted services and features, which can be viewed in the “more info” section of the communication MO1550821 in the Microsoft 365 admin center, as well as status.cloud.microsoft if the admin center is not available
November 13, 2026
Gergely Orosz, who writes the Pragmatic Engineer newsletter, said Outlook.com appeared to be down globally, as he understood it, and that Microsoft employees could not send or receive email either, along with other people using Microsoft 365. Microsoft hasn’t confirmed that its own staff email is down. In a follow-up, Orosz wrote that he had been waiting hours for an email from someone at Microsoft.
Holy cow, there’s a massive Microsoft outage going on. Outlook .com is down, globally, as I understand. Microsoft employees cannot send/receive email as well (plus everyone else using M365)
November 13, 2026
This is very bad given how important email is for comms
Postmortem will interesting
What’s being said about the cause
Tom Warren, a senior correspondent at The Verge, quoted a Microsoft 365 Status update and wrote that he is hearing the Outlook outage is down to some kind of rollout that caused servers to spike CPU usage, causing racks to go into maintenance mode and creating cascading failures. That account hasn’t been confirmed.
Microsoft hasn’t confirmed a rollout as the cause, or that racks were put into maintenance mode. Earlier, it said it hadn’t identified any recent change correlated with the start of the impact. It has said it’s investigating elevated processor usage on the affected servers, and later that a core process on those servers is becoming overwhelmed. The later work to test a previous software configuration, and to consider reverting recent configuration updates, is official recovery work. It isn’t a confirmation of Warren’s account.
I am hearing that Microsoft’s Outlook outage is down to some kind of rollout that caused servers to spike CPU usage, causing racks to go into maintenance mode and creating cascading failures
November 12, 2026
We’re actively restarting and validating the affected servers to return them to service. In parallel, we’re assessing whether reverting a small number of recent configuration updates we identified could help accelerate recovery.
November 12, 2026
The servers we returned to service can become unresponsive again once they receive traffic; we’re analyzing diagnostic data to determine what’s triggering the behavior.
November 13, 2026
An earlier Teams incident was already resolved
Earlier the same day, Microsoft resolved a separate Teams incident, TM1550488, that had affected users accessing Teams services hosted in or routed through the Americas. That disruption, which Microsoft later attributed to resource contention in the underlying infrastructure, caused delays or failures when sending or retrieving chat messages. Microsoft said customer impact was fully resolved. BleepingComputer notes that Microsoft hasn’t said whether the two incidents are related.
Knock-on effects, and how to follow the incident
OpenAI’s status page says it’s investigating elevated errors affecting the Microsoft 365 connector, and that new connections may be broken and tools are not working as expected. Reuters and ABC News reported that Anthropic said it had identified an issue with an upstream provider affecting its Microsoft 365 connector.
Microsoft hasn’t announced a restoration time. Administrators can follow EX1550543 and MO1550821 in the Microsoft 365 admin center. Microsoft has also posted updates on its public service health page at status.cloud.microsoft, and has pointed people there if the admin center isn’t available.
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