Elevated 5xx Transmissions API error rates and latency for some SparkPost customers (US hosted only)

What to do

• Check whether you use SparkPost Transmissions API - USA in eu, us. Check your stack

  Paste a package.json, lockfile, Terraform or a list of domains at down.guide/stack to see every provider you depend on.

• Confirm your retries, queues and scheduled jobs caught up after the 34m it lasted.

  Anything that failed between 2026-02-24 19:07 UTC and 2026-02-24 19:41 UTC may need a replay.

• Subscribe to SparkPost's feed to hear about the next one first. RSS feed

  https://down.guide/feed?provider=sparkpost works in Slack (/feed subscribe), Discord feed bots and any RSS reader.

Updates from SparkPost 6

1. investigatingFeb 24, 2026, 7:07 PM UTC

   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.

   provider

2. investigatingFeb 24, 2026, 7:07 PM UTC

   We are continuing to investigate this issue.

   provider

3. investigatingFeb 24, 2026, 7:25 PM UTC

   We are continuing to investigate this issue. We still see 5xx errors on mail injections and degradation.

   provider

4. identifiedFeb 24, 2026, 7:34 PM UTC

   The team has identified the root cause. There is a core networking issue that has impacted sending across the clusters.

   provider

5. monitoringFeb 24, 2026, 7:38 PM UTC

   A fix has been implemented and we are monitoring the results.

   provider

6. resolvedFeb 24, 2026, 7:41 PM UTC

   This incident has been resolved.

   provider

Corrections

None so far.

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