Outlook 2010 provides option to the users for reading emails by pressing a single key in the keyboard. This single key reading is done using the space bar. To enable the single key reading using space bar in Outlook 2010,
Click the File menu and then the options link.
In the Outlook options window, navigate to Advanced Options
In the Advanced Options screen, navigate to Outlook panes and click the Reading Pane button.
To activate single key reading, tick the check box with label as Single key reading using space bar.
Click Ok on the Reading Pane and again OK button on the Advanced Options screen to Save the changes. This is a useful feature if you are keyboard lover and want to read emails using keys rather than then mouse click.\