Outage in Mimecast
Email delivery delays on US grid
Resolved Minor
June 09, 2026 - Started 1 day ago
- Lasted about 2 hours
Incident Report
Summary AI Generated
Mimecast experienced a service disruption causing email delivery delays to Office 365 tenants, initially affecting US hosted customers and later extending to UK and South African grids. The incident lasted 2.3 hours, with the US delivery issues resolved first while mitigation efforts continued for UK and South African customers. The service team identified and worked to resolve the underlying issue affecting email delivery across multiple geographic grids.
We are aware of a service disruption that is impacting email delivery to Office 365 tenants for a subset of US hosted customers. We are investigating this issue and will post further updates here.
Components affected
Mimecast United States Grid Mimecast United Kingdom Grid Mimecast South African GridTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
1 day ago - at 06/09/2026 01:45AM
We are aware of a service disruption that is impacting email delivery to Office 365 tenants for a subset of US hosted customers. We are investigating this issue and will post further updates here.
1 day ago - at 06/09/2026 02:31AM
We have identified the issue impacting email delivery to Office 365 tenants for a subset of US hosted customers and are working to resolve it. We will provide further updates as they become available.
about 23 hours ago - at 06/09/2026 03:26AM
We have resolved the email delivery issue affecting Office 365 tenants for US-hosted customers. Mitigation efforts are ongoing for UK and ZA hosted customers, and we will provide further updates as work continues.
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