● Covered by 1 source · 1 reportMedium impact1 neutral
Microsoft Exchange Online Experiences Widespread Outage Affecting Email and Authentication
Key points
- Exchange Online outage causes email delays, failures, and authentication issues.
- Microsoft identified core authentication configuration issues as the cause.
- Tens of thousands of users are affected by the incident.
- This is the latest in a series of Exchange Online outages this year.
Widespread Service Disruption
Microsoft is currently investigating a significant service issue affecting its Exchange Online platform. The incident, identified as EX1464935, began around 5:30 PM UTC. Users are reporting widespread problems including delays or failures in sending and receiving emails, incomplete search results within mailboxes, and authentication errors when attempting to access Exchange Online services. Downdetector indicates tens of thousands of users are experiencing these issues.
Identified Cause: Authentication Configuration
Microsoft has isolated the problem to a common failure pattern related to authentication and protocol connectivity across affected Exchange Online requests. The company later confirmed that the outage stems from "issues related to a core authentication configuration used by multiple internal services within the Exchange Online infrastructure." Microsoft is analyzing service telemetry to identify the underlying source and validate remediation options.
Recurring Outages
This incident marks another in a series of outages for Exchange Online in recent months. In June, a widespread issue affected mail flow for customers across North America, APAC, and Europe. April saw resolutions for intermittent mailbox access problems impacting Outlook mobile and macOS users, as well as an outage preventing access via Outlook on the web, desktop, and other protocols. Microsoft classifies the current event as an 'incident,' indicating a critical service issue with noticeable user impact.
✨ This summary was generated by AI from the outlets' reporting listed below. It is not independently verified and may contain errors — check the original sources. How BrevFeed works →
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Reporting from
Microsoft is investigating a widespread service issue impacting Exchange Online customers, causing email delays, failures, and authentication problems. The outage, tracked as EX1464935, is attributed to core authentication configuration issues within the Exchange Online infrastructure. This incident affects tens of thousands of users and follows several other Exchange Online outages in recent months.