Also, the "Mark as unread" button is only present if you are in your inbox with the email selected. There is nothing analogous to the desktop's "Mark as unread

Also, the "Mark as unread" button is only present if you are in your inbox with the email selected. There is nothing analogous to the desktop's "Mark as unread" which is at the top of an open email, and returns you to the inbox when used. Also, there is no indication that the emails are selectable at all. The icon to the left of each email is a portrait of the sender, which in no way corresponds to the action of selecting an email.