If you have access to another user's mailbox or a resource mailbox, the following steps can be followed to open the mailbox in Outlook 2010. It will require that you already have your account setup in Outlook using Microsoft Exchange.
Outlook 2010 (Windows):
- Select File
- Click Account Settings then Account Settings again
- Double click your email account then click More Settings
- Select the Advanced tab then click Add
- Enter the email address then click OK