It’s always good to test Webhooks in an external or temporary environment before making changes in production.
RequestBin is one such tool to test your Webhooks
RequestBin gives you a URL that will collect requests made to it and let you inspect them in a human-friendly way. To get started, go to http://requestb.in/, check the box next to “Private (only viewable from this browser),” then click the “Create a RequestBin” button.
Next, copy the bin URL they provide and enter that as your Webhook URL in Netcore email API.