Idempotency

How it works

POST /api/v1/emails requires an Idempotency-Key between 8 and 200 characters. The request fingerprint includes the ordered uploaded IDs and checksums plus each direct file's filename, content type, decoded size, and checksum.

1. 1

   First request

   RouteKite creates the message and associates the key with its fingerprint.

2. 2

   Identical retry

   RouteKite returns the original message instead of a duplicate.

3. 3

   Changed retry

   RouteKite returns HTTP 409 because the key now represents different content.

Choose a useful key

• Generate one key for each logical email.
• Use a stable business identifier when possible.
• Do not reuse a key for another recipient or changed content.
• Retry the identical payload after timeouts or temporary failures.

1Idempotency-Key: order-123-confirmation