Microsoft 365 Alert : Service Degradation – Exchange Online – Some users may be unable to send email to some Microsoft hosted domains – RESOLVED
27/10/2022 08:51:00 AM (BST)
NHSmail Reference : INC32409512
Microsoft Reference : EX449975
Issue Status : RESOLVED
Issue Description : Some users may be unable to send email to some Microsoft hosted domains.
More info : Users may be unable to send email to some Microsoft hosted domains via a specific third-party cloud-based email gateway.
Impact appears to be specific to a third-party cloud-based email gateway.
Scope of impact : Any user attempting to send email messages to certain Microsoft 365 domains via a specific third-party cloud-based email gateway may be impacted.
Final Update : 27/10/2022 08:51:00 AM – Microsoft has reverted the affected infrastructure components to the last known healthy state to remediate the impact.
Root cause : A recent Windows update caused an issue on infrastructure that assists with requests to Microsoft hosted domains.
Next steps : Microsoft is continuing their analysis of the recent Windows update to gain further insight into what triggered the initial impact which will help them with identifying and preventing similar issues in future updates.