User impact: Users may be unable to run Outlook (classic) in online mode and admins may be unable to utilize the EAC.

More info: Some users may receive the following error: “HTTP 503 Service Unavailable.”

Additionally, when attempting to complete operations in the EAC, admins are returned a “503 Service Unavailable” error. This can potentially impact any EAC related operation, including but not limited to mailbox provisioning. Admins who can leverage PowerShell to complete these tasks can do so to avoid this issue.

Current status: While our efforts to manually reduce the retry traffic are ongoing, We’ve disabled the offending auto-scaling feature in a portion of the affected infrastructure. Our review of service health telemetry indicates this change has had a positive effect towards returning the service to expected functionality, and we’re performing additional validations within the portion of affected infrastructure prior to broadly implementing this change to ensure it has no adverse effects.. We anticipate the validation process will be complete by our next scheduled communications update.

Scope of impact: Any user who attempts to start Outlook (classic) in online mode or any admin utilizing the EAC may be impacted by this event.

Start time: Monday, April 14, 2025, at 12:00 AM UTC

Next update by: Sunday, April 27, 2025, at 7:30 AM UTC