Outage in Mimecast
Degraded DNS resolution on US-B Grid
Resolved Minor
March 18, 2026 - Started 24 days 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 1000+ teams
Need to monitor Mimecast outages?
Stop finding out about outages from your users. Monitor 6,020+ cloud services and get alerted the moment something breaks.
Ready to take control?
Start Free Trial
No credit card required
Set up in 2 minutes
14-day free trial
Latest Updates ( sorted recent to last )
24 days 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.
24 days 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.
Latest Mimecast outages
Login issues for customers using 2FA authentication - 2 days ago
US-B Service Degradation - 3 days ago
Email Delivery Delays - 17 days ago
Administration Console Loading Issues - 30 days ago
The Status Page Aggregator with Early Outage Detection
With IsDown, you can monitor all your critical services' official status pages from one centralized dashboard and receive instant alerts the moment an outage is detected. Say goodbye to constantly checking multiple sites for updates and stay ahead of outages with IsDown.
Start free trialNo credit card required · Cancel anytime · 6020 services available
Integrations with
