Debugging with Email Message Flow

Hey all, I have a flow that I am kicking off when an email message is recevied by the system. When I try to debug since it's not working right, I cannot do so as I cannot for the life of me figure out how to pick an email in the system to test from! This is the screen and what it's looking for. What does it want here. The ID of an icoming email preveiously recieved did not do the trick. I'm having an issue with this flow not working and I really want to run in debug mode to figure out where it's stopping in the process! I've searched google and can't find anything on how to pass this flow an email message!

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