HTTP 409
Idempotency Key Conflict
The Idempotency-Key conflicted with another in-flight request. Retry with the same key — the deduplicated response will be returned.
Example response
{
"type": "https://email.squibble.ch/docs/errors/messages/send/idempotency-key-conflict/",
"title": "Idempotency Key Conflict",
"status": 409,
"detail": "...",
"instance": "/api/v1/..."
}