611 example, because the connector is sending from the Adatum forest to the Fabrikam forest, the address space matches the domain for the forest, fabrikam.com. The Internet Address Space Properties dialog box Exchange will now route all e-mail messages that are destined to fabrikam.com (the Fabrikam forest) through this connector. 8. On the Advanced tab, click Outbound Security. 612 9. Click Integrated Windows Authentication. The Integrated Windows Authentication button in the Outbound Security dialog box 10. Click Modify. 11. In Outbound Connection Credentials, in the Account, Password, and Confirm password boxes, specify an account and password in the destination forest (in this example, Fabrikam) that has 613 Send As permissions and is an authenticated Fabrikam account. Use the following format for the account name: domain\username, where: domainis a domain in the destination forest. username represents an account in the destination forest with Send As permissions on all Exchange Servers in the destination forest that will accept e-mail messages from this connector. The Outbound Connection Credentials dialog box 12. Click OK. 614 For More Information For more information, see How to Enable Cross-Forest SMTP Authentication. How to Restrict Access by IP Address on a Receiving Bridgehead Server You can restrict access to a receiving bridgehead server by IP address and subnet address. You do this by allowing only the IP address or subnet of the connecting servers in one forest to send mail to a receiving bridgehead server in another forest. Procedure To restrict access by IP address on a receiving bridgehead server 1. Open Exchange System Manager. 2. In the console tree, expand Servers, expand < Bridgehead Serve r Name >, expand Protocols, and then expand SMTP. 3. Right-click the SMTP virtual server you want, and then click 615 Properties 4. On the Access tab, click Connection. 5. In Connection, click Only the list below to restrict access to a specified list of IP addresses. 6. Click Add, and then perform one of the following steps: Click Single Computer, and in the IP address box, type the IP address of the connecting Exchange server in the Adatum forest (the connecting forest). Repeat this step for each computer in the Adatum forest. Click Group of computers, and in the Subnet address and Subnet mask boxes, type the subnet address and subnet masks for the group of computers that host connectors to the Fabrikam forest. 616 How to Configure an SMTP Virtual Server to Resolve Anonymous Email Addresses After you have restricted access to a receiving bridgehead server, you must configure the SMTP virtual server on the bridgehead to resolve anonymous e-mail addresses. Before configuring an SMTP virtual server to resolve anonymous e-mail addresses, it is recommended that you review the topic Synchronizing Multiple Exchange 2003 Forests. Procedure To configure an SMTP virtual server to resolve anonymous e-mail addresses 1. Open Exchange System Manager. 2. In the console tree, expand Servers, expand < Bridgehead Server Name >, expand Protocols, and then expand SMTP. 3. Right-click the SMTP virtual server you want, and then click Properties. 617 4. On the Access tab, click Authentication. 5. In Authentication, ensure that the Anonymous access check box is selected, and then select the Resolve anonymous e-mail check box. How to Enable an Exchange Server to Accept Extended Message Properties Sent Anonymously If your Exchange server functions solely as the bridgehead server for cross-forest communication, you may want to enable the bridgehead server to accept extended message properties sent anonymously at the server level. If you have other SMTP virtual servers on this Exchange server, consider setting this registry key on the SMTP virtual server only. For detailed steps about how to enable an SMTP virtual server to accept extended message properties sent anonymously, see How to Enable an SMTP Virtual Server to Accept Extended Message Properties Sent Anonymously. 618 Note: If you enable this registry key on an Exchange server, the setting applies to all SMTP virtual servers on the Exchange server. If you want to configure a single SMTP virtual server with this setting, enable the registry key on the SMTP virtual server. Before You Begin Before you perform the procedure in this topic, be aware that the procedure contains information about editing the registry. Caution: Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data. 619 Procedure To enable an Exchange server to accept extended message properties sent anonymously 1. Start Registry Editor. 2. Navigate to HKLM\SYSTEM\CurrentControlSet\Services\SMTPSVC\XEXCH50 3. Right-click XEXCH50, select New, and then click DWORD Value. 4. In the details pane, type Exch50AuthCheckEnabled for the value name. By default, the value data is 0, which indicates that the XEXCH50 properties are transmitted when mail is sent anonymously. For More Information For information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=256986). 620 How to Enable an SMTP Virtual Server to Accept Extended Message Properties Sent Anonymously If you have other SMTP virtual servers on your Exchange server, consider setting this registry key on the SMTP virtual server only. If your Exchange server functions solely as the bridgehead server for cross- forest communication, you may want to enable the bridgehead server to accept extended message properties sent anonymously at the server level. For detailed steps about how to enable an Exchange Server to accept extended message properties sent anonymously, see How to Enable an Exchange Server to Accept Extended Message Properties Sent Anonymously. Note: If you enable this registry key on an Exchange server, the setting applies to all SMTP virtual servers on the Exchange server. If you want to configure a single SMTP virtual server with this setting, enable the registry key on the SMTP virtual server. . enable this registry key on an Exchange server, the setting applies to all SMTP virtual servers on the Exchange server. If you want to configure a single SMTP virtual server with this setting, enable. enable this registry key on an Exchange server, the setting applies to all SMTP virtual servers on the Exchange server. If you want to configure a single SMTP virtual server with this setting, enable. check box. How to Enable an Exchange Server to Accept Extended Message Properties Sent Anonymously If your Exchange server functions solely as the bridgehead server for cross-forest communication,