You can set up delivery receipts on the platform which will allow Zensend's API to track the delivery status of your messages and updates your app when a message has either arrived or failed to reach a destination.
You will set your own predefined URL to route the delivery receipts to. You can set this URL up here. The delivery receipt will be sent through a POST request. Please check the documentation for the list of fields to expect.
For more information you can visit the API docs.