a few months ago, everyone talk about "How to change default email icon in blackberry?"
and now i make the application when everyone start using OS 5 Blackberry

This Application can help you to change Email icon with easy.
you just run this Application
choose email
change the icon
then reset your blackberry.

but somehow my application can't work in blackberry with OS 5
Default Email Icon

With Custom Email Icons

If my Application not work in your blackberry, you can follow tutorial from this

http://blackberrymedic.co.cc/how-to-change-email-icon-in-blackberry.html

http://www.berrymanual.com/customize-blackberry-email-and-folder-icons/

http://www.berryreview.com/2009/06/22/tips-tricks-how-to-modifychange-the-yahoo-email-icon-on-the-blackberry-bold/