The Outlook app has a nice function which I think we should steal: when you go to move an email to a different folder, it pops up a short (!) list of suggestions for folders to move to, which is just populated based on the folders you've used before - it seems to be the most often used folders, which I think is more sensible than just the most recently used folders. I found this function very handy since I organise some emails in subfolders instead of just archiving them, and it made the process a lot quicker each time. I'd love to have it in Thunderbord as well.