My computer is Mac OX 10.7.5. The Mail (email) program has been upgraded. I could open up Mail 5.3 but there was no Menu Bar. (I could quit by pressing Control Q.)
When opening it up, it flashed and then the whole screen was taken up by the Mail window.
I sorted the problem by the "empirical" method, by that I mean I tried clicking on various keys and the following worked:
 Hold down the Shift Key. Keep holding it down.
 Click on Mail in dock to open it up.
 Place cursor at top of the screen so that when the Menu bar appears and then disappears you are ready to quickly do 
 Click wherever you can when menu bar flashes before it "disappears"