If you want to grant mailbox rights, use the steps below:

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 Advanced tab.
5.Click Mailbox Rights.
6.The Mailbox Rights dialog box opens.
7.Specify the appropriate level of Exchange mailbox rights.
8.Click OK.
If you want to grant the Send On Behalf permissions, use the steps below:

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 Delivery Options.
6.The Delivery Options dialog box opens.
7.Click the Add button.
8.The Active Directory object dialog box opens.
9.Enter the name of the user that the Send On Behalf permission should be granted to.
10.Click OK.
11.The name of the user is displayed in the Grant This Permission To field.
If you want to grant permissions in Outlook, use the steps below:

1.Navigate to the folder that you want to grant permission to.
2.Right-click the folder and select Properties from the shortcut menu.
3.Click the Permissions tab.
4.Click Add.
5.The Global Address List (GAL) is displayed.
6.Select the users that should have permissions to the folder, and then click OK.
7.Each user is assigned the default permission.
8.Proceed to change the permissions assigned, if necessary.