curl --request GET \
  --url https://api.example.com/api/v4/messages/{id} \
  --header ':cookie: <api-key>' \
  --header 'X-Vero-Project-Id: <x-vero-project-id>'

{
  "id": "message_123",
  "object": "message",
  "created_at": "2023-01-01T10:00+00:00",
  "updated_at": "2023-01-01T10:00+00:00",
  "provider": "provider_123",
  "campaign": "campaign_123",
  "transactional": true,
  "contents": {
    "object": "list",
    "data": [
      {
        "id": "<string>",
        "email": {
          "body": "<string>",
          "id": "content_abc",
          "object": "email",
          "subject": "<string>",
          "to": "<string>",
          "from": "<string>",
          "cc": "<string>",
          "bcc": "<string>",
          "locale": "fr-FR",
          "headers": "<string>",
          "preheader_text": "<string>",
          "plain_text": "<string>",
          "processor": {
            "mjml": "<string>",
            "type": "mjml"
          },
          "options": {
            "tracking": true
          },
          "meta": {}
        },
        "sms": {
          "id": "contents_123",
          "body": "<string>"
        }
      }
    ]
  }
}