Your mailbox is made up of folders. E-mail folders only are shown here (on the Go menu, click Mail). You can see all of the folders in your mailbox by clicking Folder List on the Go menu.
It's the stuff inside, of course.
Your main e-mail folder is the Inbox. That's where e-mail gets delivered. Your Inbox is located inside of your mailbox along with the other folders that are created by Outlook to store information. Some of the other folders that contain e-mail include Deleted Items, Drafts, Outbox, and Sent Items. You may not even think of these as folders, but knowing how much space is being taken up by them is your first step towards keeping your mailbox trim.
Note If you have a Web-based e-mail account such as MSN, you may have a separate Inbox for that account in addition to the Inbox in your mailbox.