Outage in Mimecast
Degraded DNS resolution on US-B Grid
Resolved Minor
March 18, 2026 - Started about 2 months ago
- Lasted about 5 hours
Incident Report
Summary AI Generated
Mimecast experienced DNS resolution failures on their US-B grid that caused degraded email deliverability for affected customers. The issue lasted 4.7 hours and impacted customers with temporary DNS record lookup errors. The problem was identified and mitigated, with DNS resolution performance gradually improving as the fixes took effect.
We are aware that some customers hosted on our US-B grid may be experiencing degraded deliverability due to increase in temporary DNS resolution failures. We are currently investigating the issue and updates will be posted here as they become available.
Components affected
Mimecast United States B GridTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
about 2 months ago - at 03/18/2026 06:02PM
We are aware that some customers hosted on our US-B grid may be experiencing degraded deliverability due to increase in temporary DNS resolution failures. We are currently investigating the issue and updates will be posted here as they become available.
about 2 months ago - at 03/18/2026 07:14PM
We believe we have identified the issue affecting some customers hosted on our US-B grid who experienced temporary DNS record lookup errors. We are seeing a gradual decrease in temporary DNS resolution errors as mitigation steps take effect. Customers on the US-B grid should continue to see improvement in DNS resolution performance. We will provide further updates as they become available.
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