Move between messages more fluidly
It takes a lot of clicks to get from one message to another right now. I'd suggest that while the user is on a message page, you have a drop-down menu below the main navigation tabs where you can switch back and forth between recent messages in that account. This would help with comparing past design, layout, reporting, etc.
Incorporate a messages folder preview within an opened message, as to make it easier to navigate from message to message when viewing and editing a message. Right now, when I'm in a message and need to move directly into another message, I have to click back out to general messages then the specific messages folder, then the message. Maybe there's a way to incorporate a message folders preview while in a message, so I can navigate a little quicker when bouncing in and out of emails.
Dave Mason commented
This is a great idea, but let me give you one quick work-around you can use right now: the Quick Link menu item. Its the menu with the flag icon - you can bookmark any page there (and remove it later). You could save the "View Message" page of your most recent messages in there and very quickly access them.