M365 Service Health Notification

Exchange Online service alert Incident information Title: On-premises users experiencing email delivery delays of over an hour in the Exchange Online service ID: EX221688 Status Service Restored Details Title: On-premises users experiencing email delivery delays of over an hour in the Exchange Online service User Impact: Users could have seen delays of over an hour before receiving email sent from on-premises to users hosted the cloud. More info: The problem affected all connection methods including the Outlook client and Outlook on the web. Admins may have seen the following error corresponding to this issue when reviewing client logs: 452 4.3.1 Insufficient system resources (TSTE). Final status: We've confirmed via telemetry that the configuration changes we made have successfully mitigated this issue. Scope of impact: Impact was specific to users sending email from on-premises accounts to users hosted in Exchange Online. Start time: Tuesday, September 1, 2020, at 2:00 PM UTC End time: Friday, September 11, 2020, at 11:30 PM UTC Root cause: A specific portion of infrastructure facilitating mail flow between the on-premises and Exchange Online environment wasn't processing traffic as expected during peak times, resulting in impact. Next steps: -We're continuing our investigation into the cause of this issue to develop a permanent solution. This is the final update for the event. Thank you, The Microsoft team To customize what's included in this email, who gets it, or to unsubscribe, set your Service health preferences. If you are receiving this email because your Admin added you as a recipient, please contact your Admin to unsubscribe. Microsoft respects your privacy. Review our online Privacy Statement. Microsoft Corporation One Microsoft Way Redmond, WA USA 98052