Microsoft 365 intermittent mail delivery issues
Incident Report for Mailprotector
Resolved
Microsoft 365 may still have problems if a tenant does not have an inbound connector configured. At this time, Mailprotector is considering this incident resolved. Please contact the Partner Success team from the Help Center if you have additional questions.
Posted May 10, 2021 - 18:22 EDT
Identified
We have received reports of mail delivery issues to Microsoft 365's Exchange Online. The SMTP error being returned is 451 4.7.500 Server busy. Please try again later from [52.0.x.x]. Please check affected domains by confirming the inbound connector is configured and enabled. The KB article for configuring inbound connectors is found at https://support.mailprotector.com/hc/en-us/articles/115005484203-Office-365-Inbound-Connector.

Email for affected domains is deferring and being queued on Mailprotector's transports. Once Microsoft 365 accepts the connections, queued emails will be delivered at their next retry intervals.
Posted May 08, 2021 - 15:21 EDT
This incident affected: Service Announcements.