Wow. I've been working on a presentation[1] for a conference in Tokyo[2] that uses this exact same image/diagram to visualize this concept. While it's fairly obvious to use a ven diagram to visualize this, it's still strange to see the exact same visualization that I used coming from someone else's brain too. It's a nice validation.
Showing the open rates makes it even more effective.
Showing the open rates makes it even more effective.
[1]http://prezi.com/ipuykc88vvfg/how-to-leverage-email-and-its-...
[2]http://onlab.jp/blog/archives/2012/05/onlab-data-conference-...