A draft folder is nothing but a folder that a user has in the event that they do not finish writing their email. What you want to be concerned about is their personal folder (PST). This is where a user may move mail that they want to keep for later access. For this, I would suggest that you have some personal space on the servers for your users and as they log onto each system, have them map their personal folder to that folder on the server folder and this way they can have access to it at all times.
Or simply stop running Outlook in cache mode.