Microsoft users across North America ran into a productivity choke point on Thursday as reports of service problems for Outlook, Microsoft 365 and Teams surged. Real-time outage tracker Downdetector logged thousands of complaints within hours, and some trackers showed reports swelling into the tens of thousands at the height of the incident.
What happened
Around mid-afternoon Eastern time Microsoft acknowledged it was "investigating a potential issue impacting multiple Microsoft 365 services, including Outlook, Microsoft Defender and Microsoft Purview," posting updates to social channels and its dashboard. Engineers traced the trouble to "a portion of service infrastructure in North America that is not processing traffic as expected," and began diverting traffic to alternate infrastructure to recover service.
Users most commonly reported trouble receiving and sending email in Outlook; some saw a "451 4.3.2 temporary server issue" error when trying to send or receive messages. Search inside OneDrive and SharePoint also slowed or failed for some customers, and Teams connections were affected for many organizations.
Who felt the pain
The outage hit during U.S. business hours, so schools, local governments and corporate IT teams felt the disruption sharply. Administrators reported problems in the Microsoft 365 Admin Center as well — a critical control panel for IT staff trying to diagnose and reroute traffic. Across social media and outage maps, complaints clustered around email delivery, calendar sync and collaboration tools that teams rely on every day.
This isn't the first time a widespread Outlook incident has caused headaches: an extended outage last July kept some organizations offline for many hours, a reminder of how central Microsoft’s services are to modern workflows. The scale of these platforms — now tied to Microsoft’s growing cloud and AI ambitions, such as its work on new models and services — means any hiccup can cascade through businesses and public services. (For background on Microsoft's recent cloud and AI work, see the company’s image model release in Microsoft Unveils MAI-Image-1.)
How Microsoft responded and what changed
Microsoft's status updates said the affected infrastructure was restored to a healthy state and that teams were balancing traffic across alternate systems to steady performance. In many places the company reported recovery within a couple of hours, though some users continued to see issues as traffic rebalancing completed.
The company’s official status page hosts the incident timeline and technical notes; customers are advised to monitor Microsoft 365 Service Status for the latest. The incident follows a separate, shorter disruption a day earlier that Microsoft attributed to a third-party networking issue — a reminder that both software updates and external network dependencies can ripple into service interruptions (compare with earlier Windows update-related enterprise problems documented in Windows October Update Triggers BitLocker Recovery Prompts).
For IT teams: if you still see delivery failures, Microsoft’s dashboard and admin tools are the best starting points, and many organizations may need to wait for global traffic to rebalance. For end users, temporary workarounds include retrying message sends later, using web access if desktop clients fail, or switching to alternate communication channels while services recover.
Incidents like this spotlight how dependent daily operations are on a handful of cloud providers. Microsoft’s quick public updates and infrastructure rerouting aimed to limit disruption, but the episode will likely prompt fresh scrutiny inside IT departments about redundancy, incident response plans and post-incident reviews.
Sources: Microsoft status posts and real-time outage reports.