Idempotency
Send an Idempotency-Key header on POST /emails or /emails/batch to make retries safe. Learn how Irisend deduplicates repeated requests for up to 24 hours.
- Reusing a key with the exact same request body returns the original email untouched — no new quota check, no new send.
- Reusing a key with a different body returns
409 invalid_idempotent_request. A genuinely concurrent request with the same key returns409 concurrent_idempotent_requests— retry once the first one completes. - Keys are scoped per team and expire after 24 hours — past that window the same key starts a fresh send instead of replaying.
- For
POST /emails/batch, the header is combined with each item's position, so retrying the whole batch is idempotent per item.