The default view for looking at email is to click on it review it and either delete or click on back to return to your list of emails. This can be time consuming, there is an easier method that will let you look at both at the same time. This is called the preview Pane.
Scroll down to the bottom of this screen and click on Save Changes.
Click on the dropdown arrow and select which view you would like.
No Split: will be the normal view you are use to.
Vertical Split: will show the list on the left and the message will show on the right.
Horizontal Split: will show the list on the top and the message on the bottom of the screen.