Microsoft Exchange Online experiencing intermittent mail flow issues

Incident Report for Mailprotector

Update

Microsoft Defender is restricting connectors due to false-positive reports. Please go to Microsoft Defender > Restricted Entities and unblock the listed connectors. (https://security.microsoft.com/restrictedentities)

You will need to monitor and check on this restriction for the time being. We have observed that Microsoft restricts the connector after a short time, and the unblock request must be made again.

We are continuing to monitor and investigate possible mitigation options.

Posted Jun 03, 2026 - 12:33 EDT

Identified

Microsoft is experiencing intermittent issues with mail flow. Please see their notice for reference.
https://admin.cloud.microsoft/#/servicehealth/:/alerts/EX1331830

Mailprotector is monitoring the situation. However, mail flow with CloudFilter and Shield appears to be normal. Please check logs to identify bounces or delays from Microsoft hosts to confirm potential effects from their systems.

Posted Jun 03, 2026 - 11:46 EDT

This incident affects: Issue Notice.