Allowing user to send email for another exchange user

I have an Exchange 2003 DC 2003 box with two domains being servered by the Exchange.
The server is named and these users are sending as When I go into AD users and computers to give one user the right to send email as another user It shows the email as
Even though that user is setup with email address.
Since they are being given access to the email when the delegated user tries to send from the for the other user the receive an error message saying they do not have the right to send for that user.

Any ideas on how to get around this
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to send as another exchange user, you need to grant the user permissions in Active Directory on a server running Enterprise Manager.
 Click View, Advanced Features in Active Directory

Then click the Security tab and make sure user a has access to send as user b..

if you are talking about 1 user who has 2 email addresses you will need to create 2 separate mailboxes and grant the user the right to send as the other user.
sorry.. when I say Security tab - i mean on the user prooperties..  so add user A to user B's security properties and tick nothing but the Send As box

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