Create UTM tracking token type

I think this is a great idea.  I'd adjust it slightly so that its not specifically "UTM" but any custom parameter that you want to add to all URL strings on an email.  We don't use UTM's but use instead Adobe's campaign parameter for Adobe Analytics (similar idea to Google's UTM).  In addition we have a few other use cases for other types of tracking data we pass over as part of the URL string that would be great to get captured.  

I like this idea! Currently we have to ensure we have a production step to ensure relevant links have UTM codes on them (with an internal tool that auto-creates UTM codes based on user inputs on a spreadsheet).

Tangentally related, we did build a token that decides what kind of 'tracking' we're doing on any given module in our email that is either "no tracking" (no link tracking, no munchkin tracking), "No Token" (link tracking, but no munchkin tracking), and "Tracking" (link tracking & munckin tracking). Depending on what sort of tracking we want, it helps identify where we need UTM codes at.