curl --request GET \
  --url https://api.paubox.net/v1/{api_username}/message_receipt \
  --header 'Authorization: Bearer <token>'

{
  "sourceTrackingId": "6e1cf9a4-7bde-4834-8200-ed424b50c8a7",
  "data": {
    "message": {
      "id": "<f4a9b518-439c-497d-b87f-dfc9cc19194b@authorized_domain.com>",
      "message_deliveries": [
        {
          "recipient": "recipient@host.com",
          "status": {
            "deliveryStatus": "delivered",
            "deliveryTime": "Mon, 23 Apr 2018 13:27:34 -0700",
            "openedStatus": "opened",
            "openedTime": "Mon, 23 Apr 2018 13:27:51 -0700"
          }
        }
      ],
      "total_opens": 1,
      "distinct_opens": 1,
      "total_click_count": 2,
      "clicks_per_link": [
        {
          "click_count": 1,
          "target_url": "amazon.com"
        },
        {
          "click_count": 1,
          "target_url": "ebay.com"
        }
      ],
      "unsubscribed": false
    }
  }
}