Drag to folder, from open message
 

With the Modern interface, is there any way to file an open message by dragging it to a folder on the left (as you could with the Classic interface)? Or can an open message only be filed either by clicking on "More" and selecting the folder, or by exiting the e-mail and then dragging it?

Best way is using keyboard shortcuts. Press "m" followed by the first few characters of the folder name. Once you get accustomed to doing it this way, you will find it more efficient than using the mouse to click and drag the message.

Thanks for that. It's good.