Microsoft 365 Alert – Service Degradation – Exchange Online – Some users experience errors when attempting to create shared mailboxes in Exchange Online – RESOLVED

Announcements Arpan Das

20/03/2026 16:49:00 AM

NHSmail Reference: INC46778719

Microsoft Reference: EX1256744

Issue Status: RESOLVED

Issue Description: Users experience errors when attempting to create shared mailboxes in Exchange Online.

Final Update: 23/03/2026 08:35:00 AM – Microsoft has identified that a recent service change meant to fix an issue with the communication between Microsoft Entra and Exchange Online caused impact. They have reversed the change and confirmed through service health telemetry and internal testing that the impact is remediated.

Scope of impact: Your organization is affected by this event, and some users attempting to create shared mailboxes in Exchange Online may be impacted.

Next Steps: Microsoft’s investigate the reason their service change cause the impact, they are reviewing their service change testing and validation procedures to identify and prevent similar issues in fixes moving forward.