One day I found out my reading panel had been disabled in Microsoft Outlook.
It is very inconvenient for me, because I cannot preview my email anymore.
Because of corporate's security policy, it disabled all employees' reading panel in everyone's Microsoft Outlook.
1. Start => type in "regedit" => enter
2. Find the registry : HKEY_CURRENT_USER\Software\Policies\Microsoft\office\14.0\Outlook\options
3. Change the value of property, disablereadingpane, from 1 to 0
4. Restart Microsoft Outlook