Microsoft 365 Alert – Service Degradation – Exchange Online – Users may encounter delays or failures when sending or receiving email messages in Exchange Online – RESOLVED

Announcements Arpan Das

11/03/2025 09:32:00 AM

NHSmail Reference: INC46472573

Microsoft Reference: EX1027675

Issue Status: RESOLVED

Issue Description: Users may encounter delays or failures when sending or receiving email messages in Exchange Online.

More info: Users encountering failures when sending email messages receive a Non-Delivery Report (NDR) containing an error stating “554 5.6.0 Corrupt message content”.

Final Update: 14/03/2025 04:15:00 AM – Microsoft have identified that the remaining impact relates to a separate issue which exhibits a nearly identical impact to users. They’ve confirmed that their fix completed in the affected environment and impact for this issue is remediated based on their internal monitoring. They’ll continue investigating the root cause of the remaining impact and supplying further updates in EX1030895.

Scope of impact: Any user serviced by the impacted portion of infrastructure sending or receiving email in Exchange Online may be affected.

Root cause: A recent service update intended to improve our message transport services introduced a code issue resulting in impact for a portion of service infrastructure.

Next steps: Microsoft are reviewing their service update validation procedures to detect and prevent similar issues from occurring in the future.