Tens of thousands of users across the United States lost access to their Outlook email, Teams workplace messaging, and wider Microsoft 365 services on Thursday afternoon as a widespread software and infrastructure outage crippled corporate communications.
Outage tracking data and corporate statements explain the disruption.
Outlook Disruption Affected Thousands of Users
- Peak Disruption: Downdetector recorded approximately 130,000 user reports for Outlook shortly after 1 p.m. ET on Thursday.
- Lingering Impact: By 8:00 p.m. ET, roughly 31,000 users still reported active connection and inbox loading issues, according to CNBC.
- Corporate Mitigation: Microsoft halted all deployments, diverted traffic away from failing hardware, and rolled out alternative health-check verification methods.
Server Component Failures Caused Connectivity Problems
The connectivity problems began shortly after noon on Thursday, affecting Exchange Online mailboxes across multiple connection methods in the Americas and other regions. Redmond, Washington-based Microsoft initially reported that a portion of its infrastructure was experiencing elevated load due to a number of servers being unexpectedly unavailable.
If you're having trouble accessing some Microsoft services like Outlook, OneDrive, or Copilot … yeah, a thing is going ATM.https://t.co/uyxit6UcWG
The company later determined that the strain stemmed from a specific component on affected servers that failed automated health checks. As engineers attempted to restart the unresponsive hardware, the servers frequently became unresponsive again once they received incoming traffic.
“We’re aggressively pursuing all pathways to reduce impact.”
“We've paused all deployments, we're moving additional traffic off the affected infrastructure, and we're restarting affected servers to return them to service,” the Microsoft 365 Status account wrote on X, detailing that the firm had paused all deployments and moved additional traffic off the damaged infrastructure.
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.
Disruption Across Office Workplaces and Public Services
The technological failure left corporate workers stranded throughout the workday, impacting collaboration apps like SharePoint and the Copilot AI assistant alongside core email functions.
In New York City, the Emergency Management Department warned residents of potential delays when attempting to contact municipal agencies or access online portals reliant on Microsoft infrastructure. Officials advised citizens to utilize alternative communication methods or dial 311 for non-emergency inquiries and 911 for urgent emergencies.
While Microsoft reported that mitigative actions successfully restored service health for Teams in North America, recovery efforts for Exchange Online extended well into the evening hours as engineers worked to stabilize returning servers.
Disclaimer: The information provided in this article is for educational and informational purposes only and does not constitute financial advice.
We've determined a portion of infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors. We're providing more information under EX1550543 and MO1550821 in the Microsoft 365 admin center, as well as…
Earlier coverage: Global Microsoft Outage Disrupts Teams, Outlook, and Microsoft 365 Services
More on Microsoft
We're investigating reports of users experiencing issues when accessing or using Microsoft Teams functionality in North America, and more details can be found in the Microsoft 365 admin center under TM1550488.
AGGIE ALERT – Microsoft is investigating issues affecting Microsoft 365 services today. UC Davis campus community members may experience issues using MS Outlook, Office web apps, SharePoint, Teams & other services. For resources and more information: https://t.co/41wyZiw6hX
Microsoft Outlook is down. Microsoft 365 issues are cutting people off from their email, as well as Microsoft Teams, SharePoint Online, and Microsoft 365 Copilot https://t.co/4odaKBRKQS
