Mimecast incident

Email Delivery Delays to O365

Resolved after 4 hours 55 minutes, affecting United States Grid and United States B Grid and 1 more, on September 4, 2026.

monitoring Sep 04, 2026, 10:55 AM UTC

We are aware that some customers may be experiencing email delays, with some seeing an increased volume of emails on their delivery queue. Our investigation shows that this issue is impacting emails to Office 365, coinciding with an incident reported by Office 365 on their end. We will continue monitoring and will post updates here as they become available.

Started
Sep 04, 2026, 10:55 AM UTC
Resolved
Sep 04, 2026, 03:51 PM UTC
Duration
4h 55m
Detected by Pingoru
Sep 04, 2026, 10:55 AM UTC

Affected components

United States GridUnited States B GridUnited Kingdom GridSouth African GridAustralian GridGerman GridCanadian GridOffshore GridOffshore Grid (Offshore Grid — Email Processing)

Update timeline

  1. monitoring Sep 04, 2026, 10:55 AM UTC

    We are aware that some customers may be experiencing email delays, with some seeing an increased volume of emails on their delivery queue. Our investigation shows that this issue is impacting emails to Office 365, coinciding with an incident reported by Office 365 on their end. We will continue monitoring and will post updates here as they become available.

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