Microsoft have completed the deployment of the fix within an isolated section of our internal infrastructure. They're now conducting targeted restarts of machines containing the fix to verify its effectiveness. Early indications suggest the fix is producing the desired effect but they're closely monitoring our diagnostic telemetry to ensure impact is being fully mitigated. Once they're satisfied the fix is providing the expected relief, they'll begin deploying the fix to the wider environment.
This quick update is designed to give the latest information on this issue.
Posted Mar 14, 2025 - 16:28 UTC
Investigating
Microsoft currently have an ongoing incident whereby users are receiving Non-Delivery Reports for some emails sent externally.
If you send an email and get a reply saying it hasn't been delivered, this is likely why.
Microsoft are actively working on a fix for this, and I will keep checking the status of the incident. I will send out an update email when this is resolved.