Sending on behalf of sounds like a very easy task. Fire up Outlook, type in someone else’s name in the from box, hit send. Doesn’t quite work out that way.

Rights must be given to the user to send on behalf of. One can NOT send on behalf of a group, it must be on behalf of a user.

1.) Open up Active Directory Users and Computers.
2.) Click on the View Menu and select Advanced Features
3.) Select the user that you want to send on behalf of
4.) Right click the user and select Properties
5.) Click on the Security tab
6.) Click on the Advanced button
7.) Click on the Add button
8.) Type the username you want to give permissions to
9.) At the bottom of the list, select Send As
10.) Click OK to all the dialog boxes
11.) In the properties of the user you want to send on behalf of, click on the Exchange General tab
12.) Click the Delivery Options button
13.) Click the Add button
14.) Type in the username you want to give permissions to
15.) Click OK to all the dialog boxes