具体步骤：
1. Start Exchange System Manager.
2. Expand Global Settings, right-click 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 about how to enable any one or more of these filtering types, read their associated help.
5. Expand Servers, expand the Exchange Server server, expand Protocols, expand 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.
