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Improve Exchange 2003 Internet connectivity, mail flow and performance

Learn how to configure SMTP virtual servers, connectors, bridgeheads and routing groups to improve Exchange 2003 Web connectivity and email performance.


Internet connectivity on Microsoft Exchange Server 2003 is enabled by default, but larger organizations with multiple Exchange servers or domains may want to modify their Web connections to improve efficiency or to remove a single point of failure. This tutorial explains how to better manage email message flow between an Exchange organization and the Internet. You'll learn how to create an SMTP virtual server and then custom configure SMTP connectors, bridgeheads and routing groups to better respond to your email traffic patterns and improve performance.


   Create an SMTP virtual server
   Configure an SMTP connector as a bridgehead
   Assign an SMTP connector to a routing group
   Configure an SMTP connector to relay messages to a smart host



  Create an SMTP virtual server  Return to Top


By default, Exchange Server 2003 creates an SMTP virtual server that controls outbound security, messages and relay restrictions. When reconfiguring a default SMTP virtual server, all changes are global. By default, all SMTP traffic passes through the default SMTP connector, and any restrictions applied to the connector will affect all traffic passing over it.

To create an SMTP virtual server:


  1. Open the Exchange System Manager and navigate through the console tree to:

    Administrative Groups -> your administrative group -> Servers -> your server -> Protocols -> SMTP.


  2. Right click on the SMTP container and select New -> SMTP Virtual Server to launch the New SMTP Virtual Server wizard.


  3. The wizard prompts you to enter a name for the new SMTP virtual server you're creating. If you want to control SMTP traffic on a per-server basis, we will call this new SMTP virtual server SMTP-servername, where servername is the name of the current server.


  4. Click Next and you will be prompted to select an IP address for the SMTP virtual server from the dropdown list, or by selecting the All Unassigned option. If you select an address from the dropdown list, you must select an IP address that another SMTP virtual server is not using. If you choose All Unassigned, there must be at least one available address that is bound to one of the server's NICs, but not assigned to another SMTP virtual server.


  5. Click Finish to create the new SMTP virtual server.


  Use a connector as a bridgehead  Return to Top


In larger organizations, Exchange Server administrators may not want their SMTP virtual server configuration options to apply equally to all SMTP traffic. For example, you may want to regulate SMTP traffic on a per-domain or per-server basis. To do this, I advise creating one or more SMTP virtual servers using the instructions outlined above, and then configuring an SMTP connector to that server as a bridgehead:


  1. Open the Exchange System Manager and navigate through the console tree to:

    Administrative Groups -> your administrative group -> Routing Groups -> Connectors.


  2. Right click on the Connectors container and select New -> SMTP Connector from the menu. Windows will open an unnamed properties sheet that can be used to create the new SMTP connector.


  3. Assign a name to the SMTP connector that you are creating. You can call the connector anything you want, but I recommend using something descriptive such as SMTP Connector for servername.


  4. Click Add (under General tab) to reveal the Add Bridgehead dialog box.


  5. Select the SMTP virtual server that will act as a bridgehead for the new SMTP connector. You must choose the SMTP virtual server that you created.


  6. Click OK to assign the SMTP virtual server as the bridgehead for the SMTP connector.

In most cases, you would customize the SMTP connector now. However, first we'll generically configure the SMTP connector. To do so:


  1. Go to the Address Space tab on the properties sheet, and click Add to view the Add Address Space dialog box.


  2. Choose the SMTP option from the list and click OK.


  3. Specify an E-mail Domain and a Cost, and verify that the Email Domain option is set to * (indicating that the address space applies to all email domains), and that the Cost is set to 1.


  4. Click OK twice to close the dialog boxes.


  5. Verify in the Connectors container of the Exchange System Manager that the SMTP connector was created.

The new SMTP connector parallels an existing SMTP connector being used for Internet mail flow. With this parallel connector in place, you can customize it without interfering with the organization's primary SMTP connector. Once all customizations are complete, you can configure Exchange Server so that it uses the new SMTP connector, as well as any additional SMTP connectors, instead of the default Internet mail connector.


  Assign a connector to a group  Return to Top


The new SMTP connector that you created was configured at the routing group level. When you create an SMTP connector, it generally services the routing group in which it was created. However, if another routing group doesn't contain an SMTP connector, or if a group's SMTP connector fails, messages can be routed through another routing group's SMTP connector.

Having a default connector is preferred, but you may want to configure an SMTP connector to service a particular routing group, instead of acting as a backup connector for other routing groups. To configure an SMTP connector for only the routing group in which it resides:


  1. Open the Exchange System Manager, and navigate through the console tree to:

    Administrative Groups -> your administrative group -> Routing Groups -> your routing group -> Connectors.


  2. When you select the Connectors container, you will see the routing group's connectors displayed in the right portion of the console.


  3. Right click on the SMTP connector that you want to isolate, and select Properties.


  4. Notice that Address tab contains a section labeled Connector Scope.


  5. The Connector Scope is set to Entire Organization by default. To isolate the SMTP connector to the current routing group, select Routing Group and click OK.


  Relay messages to a smart host  Return to Top


The word relay is often associated with spam; however, configuring Exchange to act as a relay can be a beneficial. For example, Exchange 2000 Server and subsequent versions depend on Active Directory, which in turn depends on DNS.

More SMTP email resources:
Best Practices Guide: SMTP virtual server and connector configuration

Tutorial: How to use SMTP queues to troubleshoot mail flow

Tip: Understanding Exchange Server routing groups

Tip: What is a bridgehead server?


Sometimes an organization's internal DNS servers are configured solely to resolve internal names. If this is the case, Exchange Server won't be able to perform the necessary name resolution on outbound SMTP messages. To resolve this, enable DNS lookup for remote domains, usually by specifying a forwarder address, or configure Exchange to forward SMTP messages to a smart host.

Smart hosts are also useful in heterogeneous environments, such as when an organization uses Exchange Server, but it isn't the primary email platform. In such as case, you may want to configure Exchange to forward messages to your organization's primary email system for distribution.

To configure Exchange to create another mail server to act as a smart host:


  1. Open the Exchange System Manager, and navigate through the console tree to:

    Administrative Groups -> your administrative group -> Routing Groups -> your routing group -> Connectors.


  2. Right click on the SMTP connector and choose Properties.


  3. The properties sheet's General tab lets you choose between using DNS to route each address space on the connector or forwarding all mail that flows through the connector to a smart host.

By default, Exchange Server 2003 uses DNS to resolve the domain names for any SMTP messages flowing through a given SMTP connector. But some DNS servers cannot resolve external domain names. In this situation, or if Exchange Server is the primary SMTP message delivery platform, you can configure the system to forward mail through the connector to an SMTP smart host (Figure 1).

Exchange Server 2003 SMTP smart host
Figure 1. Forward SMTP messages to an SMTP smart host.

To configure Exchange to use an SMTP smart host:


  1. Select Forward all mail through this connector to the following smart hosts. The field will then become available.


  2. Enter either the fully qualified domain name of your smart host or its IP address. If you enter an IP address, you must surround the address with square brackets to differentiate it from a fully qualified domain name.

    NOTE: I don't have a smart host on my network, so I typed the word SMARTHOST into the space provided, as shown in Figure 2.

    Fully qualified domain name of smart host
    Figure 2. Enter your smart host's fully qualified domain name or its IP address.

  3. Click OK.


  4. To test if Exchange Server is attempting to forward messages to the smart host, navigate through the Exchange System Manager to:

    Administrative Groups -> your administrative group -> Servers -> your server -> Queues.


  5. Select the Queues container, and Exchange will display various queues in the right column. Initially, there may not be a queue associated with the smart host. Exchange can create a queue dynamically, as needed. To do this, use Outlook or Outlook Web Access (OWA) to send an SMTP message.


  6. Return to the Exchange System Manager and press F5 to refresh the console to view the queue associated with the smart host.

    Figure 3 shows the queue Internet Mail SMTP Connector (TAZMANIA) – SMARTHOST (SMTP Connector), which is associated with the smart host. The name of the queue will vary by system based on the name of your Exchange Server, the name of the SMTP connector and the name of the specified smart host. The fact that Exchange Server created this queue is evidence that it is working correctly.

    Internet Mail SMTP Connector queue Figure 3. Exchange Server creates a special queue for relaying messages to a smart host.

  7. For additional proof that this was created properly, double click on the queue and Exchange will display the Find Messages dialog box.


  8. Click the Find Now button, and you should see the test message that you sent displayed in the Search Results pane at the bottom of the screen, as shown in Figure 4.

    Exchange test message
    Figure 4. Locate your test message in the queue.


Brien M. Posey, MCSE
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Exchange Server, and has previously received Microsoft's MVP award for Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. As a freelance technical writer, Brien has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal Web site at

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