Original Author: Microsoft Office Online
http://office.microsoft.com
This feature requires you to use a Microsoft Exchange Server e-mail account.
You can share your e-mail, calendar, tasks, notes, and journal with other Outlook users as long as you both are using a Microsoft Exchange Server in the same organization.
To share any other folder other than the Inbox, Contacts, Calendar, Notes, or Journal, you must share permissions on the folder you want to share and each folder that is higher in the folder hierarchy. For example, to give another person access to a folder that is under Inbox in your mailbox, you must grant permissions to the Mailbox, Inbox, and the subfolder. Even though it might appear you’re granting the other person access to more folders than you want, only the items in the Inbox subfolder will be available. (more…)