● Covered by 2 sources · 4 reportsMedium impact1 negative3 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.
- The outage occurred on Monday.
- Microsoft posted about the issue on X.
- Microsoft identified the problem at 12:43 p.m. ET.
- The authentication component also impacted other services beyond Exchange.
- The outage is now a multi-day event.
- The issues are not fully resolved as of Tuesday.
- Other affected services include SharePoint, Copilot, Teams, Purview, Defender XDR, Admin Center, and Universal Print.
- The outage is tracked as EX1467029.
- The outage causes 'Server busy' errors.
- Anti-spam protections may aggravate the issue for some accounts.
- Microsoft acknowledged the incident at 02:19 AM EDT.
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.
Updates
- The outage is tracked as EX1467029.
- The outage causes 'Server busy' errors.
- Anti-spam protections may aggravate the issue for some accounts.
- Microsoft acknowledged the incident at 02:19 AM EDT.
- The outage is now a multi-day event.
- The issues are not fully resolved as of Tuesday.
- Other affected services include SharePoint, Copilot, Teams, Purview, Defender XDR, Admin Center, and Universal Print.
- The outage occurred on Monday.
- Microsoft posted about the issue on X.
- Microsoft identified the problem at 12:43 p.m. ET.
- The authentication component also impacted other services beyond Exchange.
✨ 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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How outlets covered it
Microsoft is investigating an ongoing Exchange Online outage, tracked as EX1467029, that is causing delays and "Server busy" errors for emails sent to and from external domains. This incident affects users attempting to send and receive email messages, with anti-spam protections potentially aggravating the issue for some accounts.
Microsoft 365 services, including Outlook email, experienced a multi-day outage due to a core authentication configuration issue. While significant progress has been made, services are not fully resolved and are undergoing extended monitoring. This outage impacts numerous Microsoft 365 users and services, highlighting the criticality of cloud infrastructure reliability.
Microsoft confirmed a widespread, multi-hour outage affecting Outlook and Exchange Online users, causing email delays, authentication issues, and other service degradations. The company identified an issue with an authentication component and is testing a remediation strategy to restore full functionality.
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.