Email Storage Space
Employee e-mail accounts receive 50GB of storage space. All folders, messages and attachments that are kept on the server count against the quota.
If you find that you're running low or have run out of storage space, here's what you can do. First is check your Sent Items folder. That folder contains a copy of messages that you've sent out. You can delete messages from there that you no longer need, and they'll be moved to the Deleted Items folder. Second, empty your Deleted Items folder. You can do this easily by right-clicking on the Deleted Items folder and choosing "Empty Deleted Items folder". If you would like for Outlook to empty the Deleted Items for you when you close it, click on the Tools menu, go to Options, click on the "Other" tab and check the box to empty the Deleted Items folder on exit.
If you're storing messages in folders for archiving purposes, it would be best to store them in Personal Folders. Messages stored there would be kept on your computer's hard drive instead of on the server, thus freeing up space in your mailbox. Microsoft has instructions available to walk you through how to set up Personal Folders. Please note that the two caveats to Personal Folders is that they are only accessible from the computer that they're stored on and the user is responsible for backing up the file. In the majority of cases, ITS has been able to recover Personal Folders if something happens to the computer.