Microsoft KB Archive/822943

= How to Share Simple Mail Transfer Protocol Address Spaces in Exchange 2003 =

PSS ID Number: 822943

Article Last Modified on 10/9/2003

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The information in this article applies to:


 * Microsoft Exchange Server 2003 Enterprise Edition
 * Microsoft Exchange Server 2003 Standard Edition
 * Microsoft Windows Small Business Server 2003, Premium Edition
 * Microsoft Windows Small Business Server 2003, Standard Edition

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SUMMARY
In some environments, you may want to share a Simple Mail Transfer Protocol (SMTP) address space, such as an SMTP domain, between Exchange 2003 and another e-mail system. Mailboxes on both Exchange 2003 and the foreign system will have the same SMTP domain in their addresses. This article describes how to configure Exchange 2003 to share SMTP address spaces.



MORE INFORMATION
This article assumes that Exchange 2003 accepts incoming mail from the Internet, that it looks for a matching recipient in the Exchange organization, and that it then forwards the mail to the foreign mail system. The receiving system may also do the same: it may look for matching recipients, and then forward the mail to a third e-mail system. The final system in the chain must be authoritative for the domain. That is, the final receiving system must look for a matching recipient and, if one is not found, a non-delivery report (NDR) must be generated for the message. If a receiving system looks for a match and then forwards back to the original system when a match is not found, looping messages occur.

If Exchange 2003 is the last system in the chain, do not use the following procedures to configure Exchange 2003. The final receiving system must return an NDR for any unresolved addresses. By default, Exchange 2003 returns an NDR for any unresolved addresses. If Exchange 2003 is the last system in the chain, it is better to create contacts in Microsoft Active Directory directory service for all foreign system recipients. Make sure that the target SMTP address of the contacts is similar to the following format, where provides additional address information to distinguish the address space from the typical   namespace:

@ .com

For example:

@external. .com

-or-

@sendmail. .com

There are two ways to configure Exchange 2003 to share an SMTP address space. The first method is to share only select SMTP address spaces while Exchange 2003 remains authoritative for others. This is the most flexible method. You must use this method if you create contacts in Active Directory to send mail to external recipients and if the target SMTP addresses of the external recipients match any of the SMTP domains that are configured on the recipient policies in Exchange 2003. That is, if you have the address  on one of your recipient policies, and you want to create contacts with a target address of , you must use the selective sharing method (Method 1) that is described later in this article to share the   domain name.

The second method shares all address spaces. This method is much less flexible, but the configuration can be much simpler to apply in a small environment. You cannot use this method if contacts exist for the external recipients.



Method One: Share Select SMTP Address Spaces
Exchange 2003 treats e-mail messages differently depending on whether Exchange 2003 is authoritative or nonauthoritative for a particular SMTP address space. To determine if Exchange 2003 is authoritative or nonauthoritative for an SMTP address space, follow these steps:
 * 1) Start Exchange System Manager, expand Recipients, and then click Recipient Policies.
 * 2) In the Recipient Policies pane, right-click a recipient policy, and then click Properties.
 * 3) On the E-Mail Addresses (Policy) tab, click SMTP, and then click Edit.
 * 4) Examine the setting for the This Exchange Organization is responsible for all mail delivery to this address check box. If the check box is selected, Exchange 2003 is authoritative for the SMTP domain. If the check box is not selected, Exchange 2003 is nonauthoritative for the SMTP domain.



Exchange 2003 must always be authoritative for the primary SMTP address (the one that is bold) on the default recipient policy. Otherwise, local mail flow may not occur. When you share select SMTP address spaces, a shared address space is set as nonauthoritative in Exchange 2003. If the address space that you want to share is not the primary address on the default recipient policy, click to clear the This Exchange Organization is responsible for all mail delivery to this address check box for that domain.

If you want to share the primary SMTP address on the default recipient policy, set a different address as the primary address on the default recipient policy. For this specific purpose you may want to add a new SMTP address that Exchange 2003 is authoritative for. This address might be similar to @localhost or @exchange.example.com so that its purpose is purely to maintain mail flow in the Exchange organization.

To add such a policy, follow these steps.

Note You only have to add such a policy if the address space that you want to share is currently set as the primary SMTP address on the default recipient policy. Otherwise, you only have to clear the This Exchange Organization is responsible for all mail delivery to this address check box for the domain in question.
 * 1) In Exchange System Manager, expand Recipients, and then click Recipient Policies.
 * 2) In the Recipient Policies pane, right-click Default Policy, and then click Properties.
 * 3) On the E-Mail Addresses (Policy) tab, click New, click SMTP Address, and then click OK.
 * 4) In the Address box, type @localhost, or some other address space that the Exchange organization can be authoritative for. Popular choices include: @localhost, @owa.example.com, or @exchange.example.com, where example.com is your Internet domain. You can also use the Active Directory domain name if it is different from your Internet domain.
 * 5) Verify that the This Exchange Organization is responsible for all mail delivery to this address check box is selected. This domain must be stamped on all users for them to log on to the default Microsoft Outlook Web Access (OWA) virtual server.
 * 6) Click OK.
 * 7) Click the new SMTP address, and then click Set As Primary.
 * 8) Click OK, and then click Yes two times when Exchange System Manager prompts you to update all the corresponding recipient addresses.

Now that you have a different primary SMTP address that Exchange 2003 is authoritative for, you can share the other address space. To share an address space when it is not the primary SMTP address on the default recipient policy, follow these steps:
 * 1) In Exchange System Manager, expand Recipients, and then click Recipient Policies.
 * 2) In the Recipient Policies pane, right-click Default Policy, and then click Properties.
 * 3) On the E-Mail Addresses (Policy) tab, click the SMTP address space that you want to share, and then click Edit.
 * 4) To make Exchange 2003 nonauthoritative for this SMTP address, click to clear the This Exchange Organization is responsible for all mail delivery to this address check box.
 * 5) Click OK two times.

You may now want to create a higher-priority recipient policy to make sure that users receive the correct primary (reply-to) address. To do so, follow these steps:
 * 1) In Exchange System Manager, expand the Recipients folder, right-click the Recipient Policies folder, point to New, and then click Recipient Policy.
 * 2) In the New Policy window, click to select the E-Mail Addresses check box, and then click OK.
 * 3) In the Name box, type a name for your Recipient Policy, and then click Modify.
 * 4) If this policy must be set for all users, in the Find Exchange Recipients window, click OK, and then click OK in response to the Exchange System Manager message.
 * 5) On the E-Mail Address (Policy) tab, click the SMTP domain that is shared, click Set as Primary, click OK, and then click Yes two times when Exchange System Manager prompts you to update all the corresponding recipient addresses.

The @local domain is left as a secondary proxy.

Because Exchange 2003 is now nonauthoritative for that domain, when Exchange 2003 cannot find a matching address in Active Directory, it tries to find the external path of that namespace. Exchange 2003 first looks for a connector, and then checks DNS. Unless the mail exchange (MX) record for that domain already points to the server that Exchange 2003 is supposed to send to (in many cases, the MX record points to the Exchange 2003 server itself), create an SMTP connector to route the mail to a specific host. To do so, follow these steps:  In Exchange System Manager, right-click Connectors.

Note The location of Connectors will vary if you have defined administrative or routing groups. If you have defined administrative and routing groups, expand Administrative Groups, expand Administrative Group, expand Routing Groups, expand Routing Group, and then right-click Connectors. Point to New, and then click SMTP Connector. In the Name box, type a name for the connector. Click Forward all mail through this connector to the following smart hosts, and then type the fully qualified domain name (FQDN) or the IP address of the server that e-mail for the shared SMTP address space is to be routed to.

Note Type this information inside brackets ([]). Click Add, click a virtual server on the list to be a bridgehead, and then click OK. On the Address Space tab, click Add, click SMTP, and then click OK.</li> In the E-mail domain box, type the SMTP address space without the at (@) symbol. For example:

northwindtraders.com

</li> Click OK.</li> Because Exchange 2003 must receive messages for this domain also, click the Allow messages to be relayed to these domains check box.

This setting makes it possible for all SMTP virtual servers that are listed as bridgeheads to accept messages for domain.</li> Click OK.</li></ol>

After you configure these settings, when Exchange 2003 cannot find a local address match in that SMTP domain, Exchange 2003 forwards the mail to the host that is specified on the SMTP connector that has the matching address space.

Method Two: Sharing All Address Spaces
This configuration is much simpler, but much less flexible. In this configuration, Exchange 2003 is authoritative for all address spaces. You cannot have any contacts in your directory that have a target address that matches a domain that Exchange 2003 is authoritative for. To apply this method, do the following:
 * 1) Start Exchange System Manager, expand Servers, expand , expand Protocols, and then click SMTP.

Note If you have administrative groups defined, expand Administrative Groups, expand First Administrative Group, expand Servers, expand, expand Protocols, and then click SMTP.
 * 1) In the SMTP pane, right-click the default SMTP virtual server, and then click Properties.
 * 2) On the Messages tab, in the Forward all mail with unresolved recipients to host box, type the FQDN or the IP address of the server that will receive unresolved mail.

Note Type this information inside brackets ([]).
 * 1) Click OK.
 * 2) Repeat this procedure for the default SMTP virtual server on all Exchange 2003 computers, except for any virtual server that acts as an inbound gateway for the other system. Microsoft recommends that no mailboxes reside on this server.

Important This setting only affects authoritative domains. Therefore, for any authoritative domains, messages that are sent to unresolved addresses are forwarded to the server that is specified on the SMTP virtual server. Any domains that are nonauthoritative in Exchange 2003 are not affected by this setting. Messages that are sent to unresolved addresses in nonauthoritative domains are routed to a matching SMTP connector, if one is present. If no matching SMTP connector is found, the message is sent to the server that is specified in the MX record that is found in DNS.

<div class="moreinformation_section">

For additional information about how to share SMTP address spaces in Exchange 2000, click the following article number to view the article in the Microsoft Knowledge Base:

321721 XCON: Sharing SMTP Address Spaces in Exchange 2000

Additional query words: XCON

Keywords: kbhowto KB822943

Technology: kbExchangeSearch kbExchangeServ2003Ent kbExchangeServ2003Search kbExchangeServ2003St kbSBServ2003Pre kbSBServ2003Search kbSBServ2003St kbSBServSearch

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