Hi Howard,
By default a scenario that is initiated by a Custom Webhook module that does not have a "webhook response" module will essentially return a 200 HTTP code to the sending service anytime that endpoint is called. (you can easily verify this by creating a simple scenario with a webhook and sending a payload from PostMan to that new URL and seeing what is received).
For more advanced scenarios, you can include a Custom Webhook response which will then make it so that when data is sent to the scenario, the scenario will process all steps and then won't return something to the original caller until the scenraio is complete (or errors out). You can define what gets sent (e.g. 200 is everything is okay, whereas 4xx means they did something wrong, or 5xx if you have a problem).
In short -- if you dont' add other modules, it will just return a 200 as long at that webhook exists. You can see more in the "Responding to webhooks" documentation here.
