consistency
The icons at the top of the screen are not terribly intuitive, but if you have to use the two envelopes, then please keep them in the same place whether the user is on the Inbox screen or within a specific message. On both screens, the "Move" icon is directly to the left of the trash, but on the inbox, the "mark as read/unread" is to the right of the trash, while in the email message screen itself, that option is positioned two actions to the left of the trash. I waste much time clicking the wrong icon, marking as "read" what I intended to move to a particular folder.
71st
ranked