First of all the mailbox you want to access needs to have you added to the permissions list.

See this article for sharing a mailbox, or get the adminsitrator to add the permissions on the server. Once this is done you can attach the mailbox to your profile by doing the following:

Right click on the top of the mailbox tree for your mailbox. From the pop-up list select Properties for mailbox

Click on the Advanced button on the bottom right

Go to the Advanced tab, click on Add.. and enter the mailbox name.

The new mailbox will appear as an extra set of folders below your own mailbox.

Problem:
An Exchange 2007 server on which an address list service is active cannot be found.

Solution:
START the Microsoft Exchange System Attendant service from Services.msc

1.Open the Active Directory Users And Computers management console.
2.Select the appropriate user account object.
3.Right-click the user account object, and select Properties from the shortcut menu.
4.Click the Exchange General tab.
5.Click Storage Limits.
6.The Storage Limits dialog box opens.
7.Uncheck the Use Mailbox Store Defaults checkbox so that you can configure your own mailbox storage settings.
•If you want to send a warning to the user when the user’s mailbox reaches the storage limit, enable the Issue Warning At (KB): checkbox and specify the appropriate value.
•If you want force the user to clean up a mailbox that has ignored an issued warning, enable the Prohibit Send At (KB): checkbox and then specify the desired value.
•If you want to force the user to clean up a mailbox in order to receive/send new messages, enable the Prohibit Send And Receive At (KB): checkbox and set the appropriate value for the option.
8.Uncheck the Deleted Item Retention checkbox if you want to define your own Deleted Item Retention settings.
9.Click OK.

To setup an email forward for a user within Microsoft Exchange 2007, follow the instructions below:

1) Open Exchange Management Console
2) Expand Recipient Configuration
3) Click Mailbox
4) A list of all mailboxes will be appear in the right hand pane. Right click the mailbox you wish to setup the mail forward on.
5) Click properties
6) Click the mailflow settings tab
7) Double click Delivery Options
8.) Click the check box forward to
9) Browse for the mailbox you wish to forward emails to
10) Click OK to apply settings