Outage in Mimecast
Secure Messaging Login
Resolved Minor
August 24, 2026 - Started 1 day ago
- Lasted about 5 hours
Incident Report
Summary AI Generated
Mimecast experienced a ~4.6-hour login outage affecting external users of its Secure Messaging service across all global grids, including the US, UK, Canada, Australia, Germany, South Africa, and Offshore regions. The issue stemmed from authentication failures preventing external recipients from accessing secure messages. Mitigation steps were applied to the authentication service, with improvements observed across grids as fixes were rolled out.
We are aware that some customers may be having their external users experience login issues with Secure Messaging. We are currently investigating and will post updates here as they become available.
Components affected
Mimecast United States Grid Mimecast Australian Grid Mimecast German Grid Mimecast Offshore Grid Mimecast United States B Grid Mimecast Canadian 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 08/24/2026 06:25PM
We are aware that some customers may be having their external users experience login issues with Secure Messaging. We are currently investigating and will post updates here as they become available.
1 day ago - at 08/24/2026 08:17PM
We are continuing to actively investigate login issues affecting some customers' external users with Secure Messaging. Our teams remain fully engaged in troubleshooting to identify the root cause, and we will post updates here as they become available.
1 day ago - at 08/24/2026 10:55PM
We have implemented mitigation steps to address authentication issues for external Secure Messaging users. We are seeing improvements across grids and are continuing to test and apply mitigations to the authentication service. We will provide further updates as they become available.
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