The messaging tool would be much more usable and functional with the following enhancements:
1. Add a SORT tool to sort messages by sender, recipient, date. There may be other indexes that would be helpful but these are the most visibly absent to me.
2. When closing an opened message, return the user to the same page of messages they were on when they originally opened the message
3. Leave the sender's profile picture on the message header after sending a reply. Is it safe to assume the respondent's profile picture replaces that of the original sender's profile picture partially for the purpose of indicating which emails have been replied to? That is an understandable strategy but removing the original sender's profile picture makes it quite hard to quickly to back through messages to find a particular email from a particular sender. Essentially, I am suggesting that INBOX message header profile pictures be handled the same way as the message header profile pictures in the SENT MESSAGES box.
4. Add a SEARCH feature to search messages and list them by that sender, recipient, date