I was looking around, trying to figure out an estimator of the data in my inbox (thinking maybe a Cox PH model for “Time to Read Email” or Kaplan Meier Cruve), and came across this
http://www.gmailmeter.com/
Looks pretty good -building my report now. It may take 30-90 minutes to do so! I hope they allow you to export some of the data an d to play with yourself.