Friedmar - Your screenshot shows that it's not in Full screen.
Full screen mode would put the outlook window on it's own desktop. This is critical to many OSX user. Not just for the screen space, but because of how the windows interact. When not in full screen mode, windows all gather on the same desktop which becomes chaotic.
In full screen mode, you would:
- not have the top Mac toolbar
- not have the title bar in Outlook.
For example, here is Powerpoint 2011 in Full screen:
