I would find it useful to place the folders on the right and the tasks on the left. This would have the advantage that you have both the folder navigation menu and the tasks in the field of view at the same time. I would also like to see at least the Favorites folders on the left side of the page. If I want to check a subfolder of the Inbox for new emails at the moment, I am forced to switch from the Tasks tab to the Folders tab first and then fold out the Inbox folder. That's a bit awkward. In addition, if there would be a Favorites folder bar on the left, you would see at a glance whether new e-mails were received in a Favorites folder or not.