Exchange 2003 Restrict User Email Sending

Greetings all,

I have an Exchange Server 2003 and I departmental email groups that do not need to send email, only receive.

In the Exchange System Manager, I have added the group to the Routing Groups–>First Routing Group–>Connectors–>Default Connector–>Delivery Restrictions–>Reject Messages From

I have also changed the AD User Properties->Exchange General–>Delivery Restrictions to 1 KB in attempt to stop outgoing e-mails that way

Neither are currently working. Have I missed something?

Thanks in Advance!