How to set X500 proxy addresses for Exchange Server 2003 recipients and for Exchange 2000 Server recipients

This article describes how to set X500 proxy addresses for Microsoft Exchange Server 2003 recipients and for Microsoft Exchange 2000 Server recipients.

To ensure the delivery of e-mail messages to a recipient that may not typically receive these messages, (for example, Exchange Server 5.5 distinguished names [also known as DNs] or migrated contact distinguished names), you can add an X500 proxy address to the recipient. To do so, perform the following steps:

1. Start the Active Directory Users and Computers snap-in. To do so:
   1. Click Start, and then point to Programs.
   2. Point to Administrative Tools, and then click Active Directory Users and Computers.
2. Click the container that contains the user account or contact that you want.
3. Right-click the user or contact, and then click Properties.
4. Click the E-mail Addresses tab, and then click New.
5. Click Custom Address, and then click OK.
6. In the E-mail address box, type the X500 address for the recipient, for example type the following:
   /ou=<your organization name> /ou=<your organizational unit> /cn=recipients /cn=<alias>
7. In the E-mail type box type X500.
8. Click OK, click OK, and then quit the Active Directory Users and Computers snap-in.

Use Microsoft Outlook to verify that the address resolves. For example, you can compose a new e-mail message, type the X500 address of the recipient in the To box, such as in the following example, click Tools, and then click Check Names: Try to send the e-mail message, and then verify the e-mail message delivery to the recipient by using the new e-mail address.

An X500 address can be added to a mailbox, because old e-mail messages in a migrated mailbox contain these addresses. Therefore, if this address is not present in the new system, all of the replies to these old e-mail messages receive a non-delivery report (NDR).