Microsoft Alternate On-line skilled a significant international outage on July 10, 2025, stopping thousands and thousands of customers from accessing their mailboxes throughout a number of platforms. The incident, designated as EX1112414, started at 10:20 PM UTC on July 9 and continued affecting customers worldwide for greater than 11 hours.
The outage has affected customers throughout a number of areas, together with North America, Europe, Australia, and elements of Asia. Main cities reported important disruptions, together with New York, Washington, Dallas, London, Delhi, Berlin, and Sydney.
Customers have been unable to entry their Alternate On-line mailboxes by numerous connection strategies, together with:
Outlook on the internet
Outlook desktop shopper
Outlook cellular purposes
Alternate ActiveSync (EAS)
Messaging API (MAPI)
Representational State Switch (REST) API
In response to DownDetector, over 2,100 customers reported points with Outlook companies by 9:30 AM ET on July 10, with 62% experiencing login issues, 33% dealing with server connection errors, and 5% unable to ship emails.
Microsoft’s preliminary investigation recognized {that a} portion of the mailbox infrastructure was not performing as effectively as anticipated. The corporate later decided {that a} current service replace was unintentionally stopping entry for a subset of customers, leading to intermittent service unavailability.
Additional evaluation instructed the difficulty was associated to a malfunctioning authentication element that was impairing customers’ capacity to log in and entry electronic mail companies.
Microsoft’s Response and Updates
Microsoft acknowledged the difficulty by its Service Well being Dashboard and commenced deploying corrective measures. The corporate supplied a number of standing updates all through the incident:
Preliminary Response (July 9, 10:20 PM UTC): Microsoft confirmed customers have been unable to entry their mailboxes and commenced investigating the difficulty.
Early Investigation (July 10, 3:30 AM UTC): The corporate recognized underperforming mailbox infrastructure and suspected authentication element points.
Repair Deployment (July 10, 7:00 AM UTC): Microsoft introduced it had decided the reason for the difficulty and began deployment of a repair, noting that the deployment was “progressing faster than anticipated”.
Configuration Modifications (July 10, 9:34 PM GMT+5:30): Microsoft validated that configuration adjustments have been efficient in resolving the influence within the focused infrastructure and commenced deploying the expedited configuration change globally.
The corporate acknowledged it was following protected change administration processes to make sure stability through the repair deployment.
As of the most recent replace supplied at 9:34 PM GMT+5:30 on July 10, Microsoft has validated that the configuration change has been efficient in resolving the influence in focused infrastructure and has began deploying the expedited configuration change broadly worldwide to all affected infrastructure.
The corporate is working to supply an estimated remediation timeline and continues to watch the deployment course of to make sure no extra points come up.
Through the outage, affected customers acquired numerous error messages, together with “One thing went mistaken,” “invalid licenses,” and authentication failures. Many customers reported being unable to entry vital enterprise communications and shopper paperwork.
Whereas the first Alternate On-line companies have been disrupted, different Microsoft 365 companies, together with Groups, Skype, and OneDrive, appeared to stay useful, suggesting the difficulty was particular to Alternate On-line infrastructure.
This incident follows a sample of Microsoft 365 service disruptions in 2025, together with a significant outage in June 2025 that affected Groups and Alternate On-line resulting from routing configuration points.
The present outage represents one of many extra important Alternate On-line disruptions, with its prolonged length and international scope affecting thousands and thousands of customers worldwide.
Microsoft has emphasised that that is an ongoing investigation, and customers ought to monitor the official Service Well being Dashboard for probably the most present updates on restoration efforts.
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