A new app, "Geronimo" for the iPhone, is out in a couple of days... and it is probably the most "fun" email app ever made!
It makes sorting through your emails like a game...
Here are a couple of articles about it...
The Geronimo App Notifies You When You Receive Emails From Real People
http://www.trendhunter.com/trends/emailsorting
This App Makes a Wacky Game Out of Sorting Your Email
http://www.wired.com/2015/08/geronimo-email-app/
Best wishes,
Dien
P.S. Disclaimer - I am an investor in the company that created "Geronimo"...