What should you recommend?

You are the messaging engineer for your company. Your company has a main office and two branch offices.

An Active Directory site exists for each office. Each site contains two Microsoft Exchange Server 2003 servers and one routing group. A routing group connector connects each routing group. Each routing group connector uses both Exchange servers as local bridgehead servers.

You plan to deploy Exchange Server 2007. Each office will have two Exchange Server 2007 Hub Transport servers. In each office, the Exchange Server 2007 servers will be on the same network segment as the Exchange Server 2003 servers. Exchange Server 2003 mailboxes will be moved to Exchange Server 2007 Mailbox servers that reside in the same office. Mailboxes will be moved during a six week period.

You need to recommend a message routing solution that:
Uses the local network to deliver e-mail messages from users in the local office even if the mailbox has been moved to Exchange Server 2007.
Does not interfere with how Exchange Server 2003 delivers e-mail to other Exchange Server 2003 servers.

What should you recommend?

A.
Delete the existing routing group connectors. In each routing group, create an SMTP connector that uses the Exchange Server 2007 Hub Transport servers as smart hosts.

B.
For each Exchange Server 2003 bridgehead server, add a smart host to the SMTP virtual server. Configure the smart host to deliver e-mail to the Exchange Server 2007 Hub Transport servers.

C.
Create routing group connectors between each of the existing routing groups and the routing group named Exchange Routing Group (DWBGZMFD01QNBJR). For each routing group connector, configure the local Exchange Server 2007 Hub Transport servers as the remote bridgeheads.

D.
For each Exchange Server 2003 routing group, create a Send connector. Configure the Send connector to deliver e-mail to the Exchange Server 2003 bridgehead servers. Define an Exchange Server 2003 SMTP Connector in each routing group that delivers e-mail to the Exchange Server 2007 Receive connectors on each Hub Transport server.

Explanation:
Exchange 2003 uses the routing group concept to define a set of servers joined in a high speed network link, and routing group connectors to forward messages between such routing groups. Mail servers located in the same group communicate directly with each other without requiring any connectors. Exchange 2007, on the other hand, uses the existing AD site map to define its routing topology and the Hub role to transfer mail between these sites.

Combining Exchange 2007 and 2003 machines in the same Routing Group isnt supported. Instead, when the first Hub server is installed in an existing 2003 organization, all Exchange 2007 computers hosted there are automatically incorporated in a single, global 2007 group. This is recognized by 2003 ESM as Exchange Routing Group (DWBGZMFD01QNBJR).

This default Routing Group or any Routing Group Connectors which include a 2007 Hub server, as either source or target, cant be managed by either 2003 ESM or 2007 EMC. Instead, you must use the EM Shell. When an organization is running in a mixed environment, a Routing Group Connector is used to transmit messages between 2007 Hub and 2003 Bridgehead servers. If you disable referrals on this connector, users with 2003 mailboxes wont be able to view any public folders hosted on the 2007 Mailbox servers.

http://technet.microsoft.com/en-us/library/bb125223.aspx

Use New-RoutingGroupConnector to establish a connection between the 2007 routing group and any 2003 routing group when the organization is running more than one version of Exchange.
http://technet.microsoft.com/en-us/library/aa998574(EXCHG.80).aspx

Use Set-RoutingGroupConnector to modify properties of an existing connector. Also to set the maximum message size that can pass across a connector. Use SourceTransportServers to specify servers used to send messages to the target servers. Use TargettransportServers for servers that will receive messages from the source servers. Separate multiple entries by a comma. Source and target machines must be 2007 Hub or 2003 Bridgehead servers. Values overwrite existing entries.

Legacy servers are automatically added to the ExchangeLegacyInterop USG. By default, Exchange 2007 grants group members Send to and Receive from permissions on Hub servers. Use PublicFolderReferralsEnabled to determine if users can use this connector to access a PF replica in the routing group of the target servers when a PF instance isnt available in the local group (Default, $true).

http://technet.microsoft.com/en-us/library/bb232193.aspx

http://www.msexchange.org/tutorials/Implementing-Exchange-Server-2007-coexistence-Exchange-Server-2003.html

http://technet.microsoft.com/en-us/library/bb232209.aspx