Is there a limitation to the number of e-mail account icons that will show up on your screen. I have three different e-mail accounts, and only two plus the messages icon shows up.
Does the other email icon show up when you hit menu, just not on the home screen?
if that's the case you can move your icons around. hover over the icon you want to move, hit menu, move. then drag it to where you want it and click the trackball to drop it.