ScrollView cannot handle long emails. When I write an email longer than, say 500 words, the text disappears behind the attachments bar and cannot be scrolled up. When I paste text of more than 500 words into a new message, scrolling works fine.
At any rate, I really dislike that when writing a long mail, I have to work at the very bottom of the screen (Mail does that too). I'd much rather have the scrollview scroll up zodat I always type somewhere in the middle of the screen.