Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may be unable to access Exchange Online mailboxes using multiple connection methods – RESOLVED

Announcements Arpan Das

06/03/2025 09:07:00 AM

NHSmail Reference: INC46468871

Microsoft Reference: EX1023762

Issue Status: RESOLVED

Issue Description: Users may be unable to access Exchange Online mailboxes using multiple connection methods.

More info: Affected users may also experience impact to the following scenarios:

– Outlook on the web and Outlook desktop client not loading, including when opening or composing email
– Email message delivery delays
– Calendar availability shows only busy status”
– Finding times while scheduling meetings
– Users may be unable to perform searches in SharePoint Online.
– Policies configured in the Cloud Policy service for Microsoft 365 may not be applying to the signed in user.
– Microsoft Purview features such as adaptive scope evaluations, Microsoft Purview Insider Risk management reports (user groups), Microsoft Purview Data Lifecycle Management, Microsoft Purview Data Loss Prevention (DLP) and Microsoft Purview Information Protection service may be affected in various ways.
– Email archiving, expirations based on retention and deletion of expired items may be delayed.
– Users, Groups and SharePoint Sites in scope of Adaptive scope policies may not be accurate, if there are recent changes to scope definition or user attributes.
– Users, Groups in scope of DLP Admin unit policies may not be accurate, if there are recent changes to scope definition or changes to User attributes.
– Users may be unable to use the Get Events API to access calendar events in the Microsoft Graph API.

Final Update: 07/03/2025 08:20:00 AM – After an extended period of monitoring, Microsoft have confirmed that the issue is resolved.

Scope of impact: Impact is specific to some users located or served by the affected infrastructure in North America, Europe, Japan, Canada, and United Kingdom.

Root cause: An increase in user Directory API requests is causing a section of infrastructure, responsible for facilitating mailbox access requests, to perform below acceptable performance thresholds.