The Parlo API sends transactional email and manages the sending domains it authenticates from. Marketing campaigns (audiences, templates, broadcasts) are designed and sent from the Parlo dashboard, not this API — the API is transactional-only at launch. All requests authenticate with a company API key as an HTTP bearer token: `Authorization: Bearer parlo_live_xxx`. Errors return a JSON body of the shape `{ "message": string, "code": string }`.