The compose screen could have more space for text by having the Cancel, Save as Draft, and Send buttons only at the top of the screen above the text.

Having redundant Cancel and Send buttons at the bottom of the screen takes up too much of the space for text and could cause accidental cancelation or sending.

Additionally the Cc and Bcc buttons take up too much space that could be used for text. These buttons should be initally collapsed or at least collapsible to allow more space for text.