Mailgun outage, April 2026: TLS Certificate Validation Errors for Clients Without SNI
Mailgun reported and resolved an incident: TLS Certificate Validation Errors for Clients Without SNI. It lasted 1.9 hours.
OKResolved
From Mailgun's official status page, in their words.
What happened
- Started
- Resolved
- Duration
- 1.9 hours
- Impact
- major
- Affected
- API
- Investigating
- Identified
- Monitoring
- Resolved
Why it happened
Mailgun has not given a cause in its updates. We never guess one.
How it was resolved
Mailgun marked it resolved at 16 Apr 2026, 1:34 am without a written explanation of the fix.
Timeline
Oldest first, from the first notice to the resolution. From Mailgun's official status page, in their words.
- investigating
We are currently investigating an issue where customers making HTTPS requests to our API without Server Name Indication (SNI) enabled are being presented with an expired SSL/TLS certificate. This results in certificate validation failures for affected clients.
- identified
The issue has been identified and a fix is being implemented.
- monitoring
A fix has been implemented and we are monitoring the results.
- resolved
This incident has been resolved.
What this means for a business (and what to check now)
- Retry anything that failed during the 1.9 hours.
- Enter any payments, bookings or jobs you took another way.
- If a deadline fell inside the window, keep this page as your record of the outage.
The full guide: what to do when a service you rely on is down
Other Mailgun incidents
- Route delays in EU Region, resolved after 1.1 hours
- Route delays in EU Region, resolved after 42 minutes
- Route delays in EU Region, resolved after 58 minutes
- EU Messaging Outage, resolved after 17 minutes
- Microsoft Incident Resulting in Delivery Issues to M365, resolved after 34 minutes
Hear about the next Mailgun incident as it starts
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