Post incident report:

Start: 3-November-2022 1300 UTC
End: 3-November-2022 1400 UTC
Duration: 1 hour

Summary:

Delay in processing incoming mail for Office 365 customers for a short time due to a configuration error introduced in a fix for a previous issue.

Root Cause:

On November 2nd, we applied a fix to correct an increase in false positives for some realtime link analysis. This fix contained a configuration error that decreased our processing capacity which impacted the incoming mail during the typical morning email spike in traffic. This decreased capacity resulted in a slowdown in processing for Office 365 customers. This resulted in a delay for the final delivery of the messages for the morning of November 3rd.

Mitigation Action:

We corrected the configuration error introduced in the previous fix. Shortly after fixing the error, we saw the processing rates return to normal.

Customer Impact:

On the morning of November 3rd, some Office 365 customers had a period of approximately 30 minutes where email delivery was delayed.