FAQ: How to Minimize Outlook 2003 to the System Tray?
If you have Outlook opened literally all day (and night) long, it is more of an inventory in Windows than an application. Users have a choice to not occupy a place in the task bar when minimized but rather open from the system tray, where it is readily accessible but not in the way.
Minimize Outlook to the System Tray
To minimize Outlook to a stylish icon in the Windows system tray:
Click on the Outlook icon in the system tray with the right mouse button.
Select Hide When Minimized from the menu.
Now, when Outlook is minimized, it should disappear from the task bar. To open Outlook again, double-click on the Outlook system tray icon.