How to stop e-mails being sent from a Dev/Test instance

Summary: We have a requirement to stop all e-mails being sent from our non Prod instances

Content (required):

As above, we need a method to stop all e-mails from being sent from a non prod instance, or re-directed to one central e-mail inbox. During our testing so far we have come across multiple different methods of e-mails being sent out and each one requires a different way to stop them being sent.

Is there any one way to achieve this, or if not is there any place that lists the different e-mail sources and how to stop them.