For various reasons, I use three different email clients. OSX Mail is the native program, Postbox for more enhanced functions, and Sparrow for when I’m monitoring email but not really processing it. That is, most email I simply delete immediately. The rest I will look at later with my OmniFocus to do list at the ready.
This is how my Sparrow mail client looks in normal operation ( and actual size from my desktop)
When I double click an email, it opens a new windows:
The advantage of this method is that I do not have the distraction of the email messages/content on the screen. I can quickly filter for important messages or from key people, without having to look at the content.
it’s all about suppressing the “squirrel” reflex.