A reading pane makes reading and managing emails easier by having everything in one view
Click on the settings icon at the top right of the screen and select Display settings
Select reading pane at the top of the screen
Select where you would like the reading pane to appear from the three options; right, bottom or hidden
If you choose to hide the reading pane, you will have to double click an email to read it in a new window
Select the Apply to all folders box and click OK at the top of the screen