You may have noticed that by default when you minimize Outlook it still shows in the taskbar.
To stop it from showing up right click on the Outlook icon in the notification area next to the clock then select Hide When Minimized.
Another notification balloon will pop up notifying the change and how to change it back if needed.
Now there will be additional space on the Taskbar for other programs. Now you can maximize Outlook by Double Clicking the notification icon or clicking on the notification pop up if that is enabled.