Issue ID: EX1162980

Affected services: Exchange Online

Status: Investigating

Issue type: Incident

Start time: Sep 30, 2025 at 8:11 PM EDT

More info

Impact more heavily affects Outlook.com users.

Scope of impact

Users attempting to access their mailbox in one or more Exchange Online connection methods may be impacted.

Root cause

A portion of infrastructure responsible for processing request flow traffic is operating below expected thresholds, resulting in impact.

Current status

Oct 1, 2025 at 4:14 AM EDT

Service availability is steadily improving, and the backlog of messages is being processed. We’re actively monitoring service telemetry to ensure a complete recovery.

Next update by:

Wednesday, October 1, 2025 at 6:30 AM EDT