How to Add a Recipient to the Recipient Filtering List
Exchange 2003 supports recipient filtering. Therefore, you can filter e-mail messages that are addressed to users who are not in Active Directory or e-mail messages that are addressed to recipients who are frequently targeted by distributors of unsolicited commercial e-mail messages.
Recipient filtering rules apply only to anonymous connections. Authenticated users and Exchange servers bypass these validations.
Procedure
To add a recipient to the recipient filtering list
On the Recipient Filtering tab (see the following figure) of the Message Delivery Properties dialog box, click Add.
Recipient Filtering tab in the Message Delivery Properties dialog box
For More Information
For more information about connection filtering and how it works, see "Connection Filtering" in What's New in Exchange Server 2003.