The reading pane
When the reading pane is open, it is displayed under or to the right of the main pane.
The reading pane displays the contents of any object selected in the main pane. For example, a selected message or document opens in this pane.
You can work with objects in the reading pane just as you do when they are opened in the main pane.
Opening the reading pane
To open the reading pane, click this button:
This button is only visible if you have the navigation pane open. It toggles through three states. To move the reading pane to the right of the main pane, click this button again. To close the reading pane, click this button a third time.