Exchange 2007 Mail Routing Management

Configuration that can be performed when managing mail routing for an Exchange Server 2007 organization. There are many components involved in routing messages to recipients in an Exchange 2007 organization. If you configure settings for these components, you can control how messages are transferred between Hub Transport servers, Edge Transport servers, servers that have Exchange Server 2003 or Exchange 2000 Server installed, and other Simple Mail Transfer Protocol (SMTP) servers.

The Exchange 2007 routing topology is derived from the Active Directory directory service website topology. Internal mail routing relies on the configuration of Active Directory sites and IP site links to determine the following:

● Which Exchange servers can communicate correctly.

● When to relay mail between Active Directory sites.

When routing a message to an external domain, it must be routed to the Send connector. If your Exchange 2007 organization coexists with an Exchange 2003 or Exchange 2000 organization, you must use a routing group connector. The following sections outline how to configure routing components and how to troubleshoot routing.

Active Directory Sites

Active Directory sites are not managed by an Exchange administrator. Active Directory sites can be created, deleted, or modified only if they have permissions assigned to the Active Directory Enterprise Administrators group. However, because the Exchange routing topology is derived from the Active Directory site topology, Exchange administrators can apply attributes that apply only to Exchange to Active Directory sites that are considered only for Exchange 2007 routing.

In an Exchange organization, it may be necessary to force all mail delivery to be relayed through a special Active Directory website. In this case, connectivity may prevent direct SMTP relay between sites. Therefore, the mail must be relayed through the intermediate website before sending the mail to the destination address. Depending on the internal organization of the Exchange organization, administrators may also want to relay all mail through a special website. You can use the Exchange Management Shell task to designate an Active Directory site as a central site.

Use the Set-ADSite cmdlet to designate an Active Directory site as a central site. As long as there is a central site on the least expensive routing path for delivering mail, the messages are queued and processed by the Hub Transport server in the central site and then relayed to the final destination. When an Active Directory site is configured as a central site, the routing path that contains the site is always relayed through the central site.

Active Directory IP Website Links

Similar to Active Directory websites, Active Directory IP website links are not managed by an Exchange administrator. You must have permissions assigned to the Active Directory Enterprise Administrators group to create, delete, or modify Active Directory site links. However, because the Exchange routing topology is derived from the Active Directory site topology, Exchange administrators can apply attributes that apply only to Exchange to Active Directory sites that are considered only for Exchange 2007 routing.

By default, Microsoft Exchange uses the overhead allocated for IP site links for Active Directory replication to calculate the routing topology. If you find that the overhead of Active Directory site links and network traffic patterns is not optimal for Exchange 2007 after recording the existing Active Directory site and IP site link topology, you can adjust the cost of Microsoft Exchange calculations. As an Exchange administrator, you cannot and should not use Active Directory tools to modify the overhead allocated for IP site links, instead use the Set-ADSiteLink cmdlet in the Exchange Management Shell to assign Exchange-specific overhead to IP site links.

When you assign Exchange overhead to an IP site link, Exchange overhead overrides the Active Directory overhead for message routing. When calculating the routing path with the lowest cost, the route only considers the Exchange overhead.

What's New in Exchange 2007 Service Pack 1

Microsoft Exchange Server 2007 Service Pack 1 (SP1) provides support for the configuration of the maximum message size limit on Active Directory IP site links. By default, Exchange 2007 does not impose a maximum message size limit on messages that are relayed between Hub Transport servers in different Active Directory sites. If you use the Set-AdSiteLink cmdlet to configure the maximum message size for an Active Directory IP site link, the route will be sent for messages that are larger than the maximum message size limit (the value configured on any Active Directory site link in the least expensive routing path) Report (NDR). This configuration is useful for limiting the size of messages sent to remote Active Directory sites that must communicate over low bandwidth connections.

Send connector

During the Exchange 2007 transport server sending a message to the destination address, the message is sent to the next hop through the Send connector. The Send connector controls the outbound connection from the sending server to the receiving server or the target email system. The address space of the Send connector specifies the following conditions:

●Recipient domain to which this connector routes emails

●Transport type

●Special send connection Overhead of address space allocation on the device

By default, no explicit send connectors are created when you install the Hub Transport server role or the Edge Transport server role. However, when routing messages internally, the implicit in-organization send connector is used. End-to-end mail flow can only be achieved if one of the following conditions is met.

● The Edge Transport server has been subscribed to the Active Directory website using the Edge Subscription process.

●You have manually configured the Send connector and Receive connector to route Internet mail.

Protocol logging for Send connectors within an organization is disabled by default. You can use the Set-TransportServer cmdlet to enable or disable protocol logging for Send connectors in your organization.

Routing Group Connector

If Exchange 2007 coexists with Exchange 2003 or Exchange 2000 in the same organization, you must configure it in a global Exchange 2007 routing group with earlier versions of Exchange Server Configure routing group connectors between routing groups. When the first Hub Transport server role is installed in an existing Exchange organization, the first routing group connector is created and configured between Exchange 2007 and Exchange 2003 or Exchange 2000.

You must use the Exchange Management Shell to configure a routing group connector that uses an Exchange 2007 Hub Transport server as the source or destination server. To support coexistence with Exchange 2003 and Exchange 2000, all computers running Exchange 2007 are automatically placed into a routing group when the first Hub Transport server role is installed. Routing groups in Exchange 2007 are recognized as Exchange routing groups (DWBGZMFD01QNBJR) in Exchange System Manager for Exchange 2003 and Exchange 2000. Exchange System Manager for Exchange 2003 and Exchange 2000 cannot be used to manage Exchange 2007 routing groups and any routing group connectors that have Exchange 2007 Hub Transport servers as source or destination servers.

Exchange 2007 SP1 New features

Exchange 2007 SP1 provides support for the maximum message size limit routing group connector configuration. By default, Exchange 2007 does not limit the maximum message size for messages relayed through the routing group connector. If you use the Set-RoutingGroupConnector cmdlet to configure the maximum message size allowed by the routing group connector, the route generates an NDR for any message that exceeds the maximum message size limit configured by any routing group connector in the least expensive routing path. This configuration can be used to limit the size of messages sent to remote Exchange Server 2003 and Exchange 2000 Server servers that must communicate over a low-bandwidth connection.

Troubleshooting Routing

Exchange 2007 provides tools and detailed logging resources to help you troubleshoot mail flow issues. The following diagnostic tools are available in the toolbox of the Exchange Management Console:

●Exchange Server Best Practices Analyzer Use the Best Practices Analyzer to check the configuration and health of your Exchange topology. This tool automatically collects and checks the configuration information for your Exchange organization and summarizes the findings in the report. The report lists the issues by severity and provides suggested solutions to the problem. In addition, the tool provides a list of recent changes and a detailed summary of the Exchange organization configuration.

●Exchange Mail Flow Troubleshooter Use the Exchange Mail Flow Troubleshooter to help diagnose problems with mail flow and delivery. Use this tool to select mail flow symptoms, analyze the configuration, and output the findings to the report.

●Mail Tracking Use the Message Tracker to check the contents of the message tracking log.

● Queue Viewer Use the Exchange Queue Viewer to view and manage Exchange mail queues.

Exchange 2007 SP1 New Features

The Routing Log Viewer is a new tool in Exchange 2007 SP1. You can use this tool on an Exchange 2007 SP1 server that has the Hub Transport server role or the Edge Transport server role installed. You can launch the Routing Log Viewer through the <toolbox" node of the Exchange Management Console.

In earlier versions of Exchange Server, WinRoute (Winroute.exe) could be used to connect to the Exchange Routing Engine service on port 691. There is no routing engine in Exchange 2007. The Routing Log Viewer allows administrators to open routing log files that contain information about how the routing topology displays the server. You can compare the routing log files and then determine what changes have occurred in the routing topology between the two time periods. Use this tool to determine the changes that have occurred in the routing topology and to assess whether these changes can cause problems.