1. Run the Exchange System Manager.
2. Expand Global Settings>Message Delivery, and then click Properties.
3. Click the Recipient Filtering tab, click to select the Filter recipients
who are not in the Directory check box, and then click OK.
4. When you receive the following message, click OK:
Connection, Recipient, and Sender Filtering must manually be enabled on
specific SMTP virtual server IP address assignments as they are not enabled
by default. For more information on how to enable any of the above filtering
types, read their associated help.
5. Expand Servers>Server name>Protocols>SMTP, right-click Default SMTP
Virtual Server, and then click Properties.
6. On the General tab, click Advanced.
7. Click Edit, click to select the Apply Recipient Filter check box, and
then click OK three times.
Note 1: After you enable recipient filtering, Exchange validates the e-mail
address before Exchange accepts the e-mail message. In this scenario, if no
match for this e-mail alias appears in Active Directory, an NDR is still
generated. However, in this scenario, it is the responsibility of the
sending SMTP server instead of your Exchange server to generate and to
deliver the NDR.
Note 2: Recipient filtering is only available in Exchange 2003 Server.
