Posted 04 February 2013 - 21:00
Our practice that we tell people to do is the following.
You can create as many folders as you like on your inbox However, if you want to back them up and store them locally to reduce the storage space you are using on the server, it is required you make a PST locally on your computer. (so long as you move it to the PST it is no longer on the server)
We limit our users to 750Mb for their mailbox.