Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may experience delays in loading images and attachments in Exchange Online email messages – RESOLVED

10/11/2025 09:02:00 AM

NHSmail Reference: INC46677514

Microsoft Reference: EX1183800

Issue Status: RESOLVED

Issue Description: Users may experience delays in loading images and attachments in Exchange Online email messages.

More info: Delays may be up to ten seconds. Some users’ signature add-in images may also be affected.

Final Update: 14/11/2025 08:10:00 AM – Microsoft have confirmed that their fix deployment has reached the vast majority of the affected environment and determined from monitoring service telemetry that this issue is no longer occurring.

Scope of impact: Some users may experience delays in loading images and attachments in Exchange Online email messages. This section may be updated as our investigation continues.

Root cause: A recent update to an authentication component of attachment logging introduced a regression which is causing the portion of service infrastructure responsible for loading signature add-in images to operate in a suboptimal state.

Next steps: Microsoft are reviewing their validation and updating procedures to better detect and prevent issues like this prior to deployment in the future.