new option for Reading mail - "Do not mark Read on server".
It is very useful when you use phone to review mails and monitoring of what happening in your company and react on really urgent mails only, but you do not want to mark mail as Read other mails as you want to keep it as unread and answer it later from office, and you do not want to forget to answer.
Such option already exists in other mail client "Touchdown for Smartphones". Really miss it your mail client.