From letalis0:

This is either a request for future builds or a question on how to do this:

Basically, putting the guild tag on messages from people in your actual guild so you know if they are using GreenWall or not. Is it possible?

I'm accepting this with a scope change. I don't want to add message tagging, but we can leverage the API to determine which guild members are not using GreenWall.

On second thought, closing this out as it would now be a duplicate of #45.