We're using Triggered Sends for the first time.
As this is the first time we're using this type of send, we're slightly terrified of emailing people we shouldn't be when testing. Therefore, we'd like to add an exclusion script to exclude anyone in All Subscribers (making sure of course that the requested email address in the test isn't in All Subscribers).
We've established how write a script to exclude people who are present in a Data Extension, but not in All Subscribers.
How exactly would we do this?