Tim; are the buttons that you have made conforming to some type of UI spec on size? Because, I think that it could be further tweaked...

...for example, the From button could be done away with and put into a submenu (or, that could be something captured when the user clicks on 'compose" on the screen before, asked via a popup dialog of all the accounts available).

..the spelling and attachment buttons are probably double the size they need to be, I'd say about half as wide, but keep the same height. Then move the "Save Draft" button either to a submenu, or remove it entirely and the application would just save all emails as drafts by default with the user simply needing to turn that feature off if they didn't want it.

...The "To" button would remain, but it would change its context from saying "To" to having the name of the person (if a single recepient) or an elipses (...) if there are more than one person. This works well because the ideal behind email is just to point the message and go. There's no need to see the "To" as an empty field.

...The "Subject" button would likewise change once the user has imputted a subject. Because we have gained some more space here with the removal of a button and the making smaller of others, we then have room to show most of the subject. I would say that if its something that could be done in two lines in a smaller system font, that this option should be taken if the subject goes long.

...I agree that there should be more space for the body as you've designed.

edit/add: I think that the attachments button would be better served at the bottom with the other email composition buttons on a second look. This again adds more space at that top menu area.