Send a templated message to one or more recipients. Provide the template once — inline in message_template with [placeholder] tokens, or as a saved template by its event key — then supply each recipient's values in template_variables.

• Set a default sender and event at the top level; override either per recipient.
• Up to 250 recipients per request.
• An unknown event, or neither event nor message_template, fails the whole request.

Response. HTTP 200 with a task_id and one entry per message. status is false when any message failed: failed entries come first and carry error (hex code) and details; accepted entries carry message_uuid (and conversation_uuid on two-way channels). Match entries by internal_id. Final delivery status is sent asynchronously to your configured webhook.

Authentication: stream token in the Authorization header (see Authentication in the API Overview).

{
  "recipients": [
    {
      "contact": {
        "display_name": "John Doe",
        "email": "test@example.com",
        "external_id": "crm-1001",
        "first_name": "John",
        "last_name": "Doe",
        "phone": "12125551234"
      }
    }
  ]
}

{
  "messages": [
    {
      "conversation_uuid": "e2a489db-bb8a-4f51-9692-726153599c57",
      "internal_id": "1001",
      "message_uuid": "a61e5bfe-c82b-448a-815b-32de8bf22089"
    }
  ],
  "status": true,
  "task_id": "ca550f7e-9eb5-45b3-9830-e82b407ede02"
}