Exchange Online Outage Triggers External Email Delays With "Server Busy" Error, Microsoft Confirms

If you’ve been struggling with external email delivery today, Microsoft has acknowledged the Exchange Online outage. The incident is tracked under EX1467029 in the Microsoft 365 admin center (via BleepingComputer). The company has confirmed that delays when sending or receiving messages from external domains, and some mailboxes are showing intermittent “Server busy” errors.

Exchange Online emails are facing delays, Microsoft confirms

The issue is classified as a service degradation and appears to affect multiple regions. Reports from administrators mention SMTP errors and queued messages that eventually deliver after a delay.

In the official advisory, Microsoft has noted that it has identified the underlying cause and is now applying a mitigation. Delivery should gradually return to normal, though queued messages may take additional time to clear.

Do note that internal Exchange Online traffic appears less affected, with external domains bearing the brunt of the disruption. Third‑party providers, including SuperOffice, have also reported delays involving Microsoft 365 and Outlook.com mailboxes.

This isn’t the first time Microsoft 365 services have had problems. Earlier this week, a massive outage knocked down Teams, Outlook, and more.

This is a devloping story…