Microsoft's Exchange Online Outage Causes Email Delays, 'Server Busy' Errors
Microsoft is working to resolve an ongoing Exchange Online outage that has caused email delays and 'Server busy' errors. The issue began on September 4 at 02:19 AM EDT, when users started reporting intermittent problems sending and receiving emails from external domains.
The company first acknowledged the incident under EX1467029 and is investigating reports of 'Server busy' errors affecting multiple mailboxes. Microsoft says that anti-spam protections may be contributing to the issue for a subset of users.
Users who experience email delays or 'Server busy' errors are advised to periodically retry sending emails, as the service should attempt to resend impacted messages. If an initial sender received an NDR (Non-Delivery Report) after 24-72 hours, they will need to send a new email.
Microsoft has not provided a timeline for full remediation but is working to understand the root cause of the issue and will provide further details later today. The company has flagged this incident as noticeable user impact, which usually involves significant disruptions.