Outage in SparkPost
Elevated 5xx Transmissions API error rates and latency for some SparkPost customers (US hosted only)
Resolved MajorIncident Report
Summary AI Generated
SparkPost experienced elevated 5xx error rates and latency on their Transmissions API for US-hosted customers due to a core networking issue affecting sending clusters. The incident impacted email injection capabilities for some customers over a 37-minute period. The team identified the root cause, implemented a fix, and resolved the issue after monitoring confirmed restoration of normal service.
We are experiencing an elevated level of errors and latency on the Transmissions API (injection API) for some SparkPost customers. Please retry any 5xx error.
Note: This issue does not impact SparkPost customers hosted in the EU.
Components affected
SparkPost Transmissions API - USATrusted by 1000+ teams
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Latest Updates ( sorted recent to last )
RESOLVED
about 2 months ago - at 02/24/2026 07:41PM
This incident has been resolved.
MONITORING
about 2 months ago - at 02/24/2026 07:38PM
A fix has been implemented and we are monitoring the results.
IDENTIFIED
about 2 months ago - at 02/24/2026 07:34PM
The team has identified the root cause. There is a core networking issue that has impacted sending across the clusters.
INVESTIGATING
about 2 months ago - at 02/24/2026 07:25PM
We are continuing to investigate this issue. We still see 5xx errors on mail injections and degradation.
INVESTIGATING
about 2 months ago - at 02/24/2026 07:07PM
We are continuing to investigate this issue.
INVESTIGATING
about 2 months ago - at 02/24/2026 07:07PM
We are experiencing an elevated level of errors and latency on the Transmissions API (injection API) for some SparkPost customers. Please retry any 5xx error.
Note: This issue does not impact SparkPost customers hosted in the EU.
Latest SparkPost outages
Increased bounce or delay rate for Apple domains - 9 days ago
Email delivery in US region affected - about 1 month ago
Outbound message delivery is delayed/slow for some SparkPost customers (US and EU regions) - about 1 month ago
Microsoft Mail Delivery Delays and Temporary Rejections - about 2 months ago
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