curl --request POST \
  --url https://api.tinyinbox.app/sites/{siteId}/test-message \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "message": "<string>"
}
'

{
  "message": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "conversationId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "senderType": "visitor",
    "body": "<string>",
    "createdAt": "2023-11-07T05:31:56Z",
    "senderId": "<string>"
  }
}