text: Side note - if reporting on this stuff at an individual level is really important, you may want to look into something like Litmus - it's great for email testing but also allows you to input analytics tracking code into your emails with an individual ID for each recipient. You can't track clicks with it, but you can get a lot of other valuable analytics data at both a high level and a granular individual level. It is a subscription service but pretty cheap, to be honest.