Errors

How SNDR signals errors, and what to do about them.

SNDR uses standard HTTP status codes plus a structured error envelope.

json

{
  "error": {
    "code": "invalid_recipient",
    "message": "Recipient \"not-an-email\" is not a valid address",
    "request_id": "req_8a91lk2"
  }
}

Common codes

invalid_request — your payload was malformed
unauthenticated — missing or invalid API key
rate_limited — slow down or contact us
domain_not_verified — verify your sending domain first
recipient_suppressed — recipient is on your suppression list