A widespread Microsoft Outlook outage disrupted email access for users in Houston and across the United States on Thursday. Customers reported problems loading inboxes, sending messages and connecting to other Microsoft 365 services.
Microsoft confirmed it was investigating problems affecting Exchange Online mailboxes in the Americas. The company warned that users in other regions could also experience connection failures.
Microsoft Outlook Outage Draws Thousands of Reports
Outage reports began rising around midday Thursday. Nearly 130,000 Outlook reports appeared on Downdetector shortly after noon Central Time.
Reports later declined from that peak. However, some users continued to experience problems sending or receiving email. Others could not load their inboxes or sign in.
Houston was among the markets potentially affected by the outage across the Americas. Microsoft did not immediately release regional totals for Houston or Texas.
The disruption affected several connection methods. Those included Outlook on the web, Exchange ActiveSync, Microsoft’s messaging interface and other application connections.
Other Microsoft 365 Services Affected
Outlook was not the only Microsoft product experiencing problems. Users also reported disruptions involving Teams, Copilot and other Microsoft 365 tools.
Microsoft said the wider outage could affect Exchange Online, SharePoint Online, Microsoft Teams, Microsoft 365 Copilot and Microsoft Defender XDR. Some businesses rely on these services for email, meetings, file storage and security monitoring.
Earlier Thursday, Microsoft reported separate Teams problems in North America. The company said those issues had been restored, although some customers continued reporting connection errors.
The outage created potential delays for workplaces, schools and organizations throughout the Houston area. However, the full local impact remained unclear Thursday afternoon.
Microsoft Investigates Unavailable Servers
Microsoft said part of its infrastructure was experiencing an elevated load across several regions. The company later found that some servers had become unexpectedly unavailable after failing automated health checks.
Engineers paused deployments and began moving traffic away from the affected infrastructure. Microsoft also restarted servers and redistributed connections across its worldwide network, according to WIRED.
Microsoft had not announced a final cause or full restoration time as of Thursday afternoon. The company tracked the Exchange Online problem under incident number EX1550543. A broader Microsoft 365 disruption was listed as MO1550821.
There was no confirmed evidence that a cyberattack caused the outage.
What Houston Users Should Do
Users experiencing problems should avoid repeatedly resetting passwords or reinstalling Outlook. Those actions are unlikely to resolve a service-level outage and could create additional account issues.
Businesses can use phone calls, text messages or other approved communication platforms during the disruption. Important messages may also arrive after service returns because email systems often retry delayed deliveries.
Microsoft 365 administrators can follow incident updates through the service health section of the admin center. Other customers can monitor the public Microsoft service status page.
Houston-area users should confirm that delayed messages were delivered once Outlook service stabilizes. Businesses should also review their inboxes and outboxes for time-sensitive communications.