A number of updates were posted by MIcrosoft across the night, with the start of service recovery of exchange being seen around 03:30 GMT.

All queued emails have been sent in US and CA regions, and the service is fully operational.

Microsoft have reported service degradation to multiple Microsoft 365 components, with customers receiving a "451 4.3.2 temporary server issue" error message when attempting to send or receive email through Outlook.

More information is available from Microsoft's cloud status pages at https://status.cloud.microsoft/

We are still experiencing server-side email delays due to these issues, however please rest assured that email routed through server-side injection will be delivered to the recipients when Microsoft's services recover.

We are currently seeing server-side email delivery delays due to a Microsoft 365 outage, as confirmed by Microsoft at 7:37 PM on X: https://x.com/msft365status/status/2014422298506285161:

"We’re investigating a potential issue impacting multiple Microsoft 365 services, including Outlook, Microsoft Defender, and Microsoft Purview. Further information can be found in the admin center under MO1221364."