{
  "object": "page",
  "entry": [
    {
      "id": "PAGE_ID",
      "time": 1458692752478,
      "messaging": [
        {
          "sender": {
            "id": "USER_ID"
          },
          "recipient": {
            "id": "PAGE_ID"
          },
          "timestamp": 1234567890,
          "optin": {
            "ref": "PASS_THROUGH_PARAM"
          }
        }
      ]
    }
  ]
}
