Outage in Microsoft 365
Some users may experience issues when accessing their Exchange Online mailbox via one or more connection method
Resolved Minor
March 16, 2026 - Started 1 day ago
- Lasted about 6 hours
Incident Report
Summary AI Generated
Microsoft 365 Exchange Online experienced a 5.9-hour service incident where some users, particularly in Europe, encountered errors and failures when accessing their mailboxes through multiple connection methods including Outlook on the web, Outlook desktop, Exchange ActiveSync, and other Exchange Online protocols. Microsoft identified a backend issue preventing services from responding as expected, causing mailbox access delays across regions. The issue was resolved through natural recovery with Microsoft monitoring telemetry data to confirm service stability was restored.
Title: Potential issues accessing mailboxes via one or more connection methods
User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods.
Current status: We're investigating a potential issue and checking for impact to your organization. We'll provide an update within 60 minutes.
Components affected
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Latest Updates ( sorted recent to last )
about 20 hours ago - at 03/16/2026 03:28PM
Title: Some users may experience issues when accessing their Exchange Online mailbox via one or more connection method
User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods.
More info: Users may experience errors or failures when attempting to access their mailbox. Impacted connection methods include but may not be limited to:
- Outlook on the web
- Outlook desktop
- Exchange ActiveSync
- Other Exchange Online connection protocols
Current status: While telemetry continues to show the issue is no longer occurring for affected users, we're continuing to monitor service health to assess whether any additional actions are required to ensure sustained recovery.
Scope of impact: Impact is specific to some users attempting to access their mailbox via any of the connection methods detailed above.
Next update by: Monday, March 16, 2026, at 4:30 PM UTC
about 21 hours ago - at 03/16/2026 02:45PM
We’re continuing to monitor service health to identify whether any additional actions are required to ensure longstanding recovery. Our telemetry continues to indicate the issue is no longer occurring for affected users.
This quick update is designed to give the latest information on this issue.
about 22 hours ago - at 03/16/2026 02:19PM
Title: Some users may experience issues when accessing their Exchange Online mailbox via one or more connection method
User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods.
More info: Users may experience errors or failures when attempting to accessing their mailbox. Impacted connection methods include but may not be limited to:
- Outlook on the web
Current status: Internal reports and service monitoring telemetry indicate that the issue is no longer occurring for affected users. We’ll continue to monitor service health to ensure ongoing stability.
Scope of impact: Impact is specific to some users attempting to access their mailbox via any of the connection methods detailed above.
Next update by: Monday, March 16, 2026, at 3:30 PM UTC
about 22 hours ago - at 03/16/2026 01:30PM
Title: Some users may experience issues when accessing their Exchange Online mailbox via one or more connection method
User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods.
More info: Users may experience errors or failures when attempting to accessing their mailbox.
Impacted connection methods include but may not be limited to:
- Outlook on the web
Current status: We’ve identified a backend issue that’s preventing some services from responding as expected, resulting in mailbox access delays. We’re investigating this behavior across regions to better understand the impact and determine next steps. We’re seeing signs of service recovery and will share additional updates as our investigation continues.
Scope of impact: Impact is specific to some users attempting to access their mailbox via any of the connection methods detailed above.
Next update by: Monday, March 16, 2026, at 3:30 PM UTC
1 day ago - at 03/16/2026 11:23AM
Title: Some users may experience issues when accessing their Exchange Online mailbox via one or more connection method
User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods.
More info: Users may experience errors or failures when attempting to accessing their mailbox.
Impacted connection methods include but may not be limited to:
- Outlook on the web
Current status: We’re currently reviewing service telemetry data to help identify the root cause and next steps required to mitigate impact.
Scope of impact: Impact is specific to some users located in Europe attempting to access their mailbox via any of the connection methods detailed above.
Next update by: Monday, March 16, 2026, at 1:30 PM UTC
1 day ago - at 03/16/2026 10:56AM
Title: Potential issues accessing mailboxes via one or more connection methods
User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods.
Current status: We're investigating a potential issue and checking for impact to your organization. We'll provide an update within 60 minutes.
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