Managing the Hub Transport Server Role • Chapter 6 317 So how do you set up your routing topology in Exchange Server 2007? Well, you don’t! Exchange Server 2007 is a site-aware application, which means it can determine its own Active Directory site membership and the Active Directory site membership of other servers by querying Active Directory. So, instead of using its own routing group topology, Exchange makes use of the AD directory service site topology to determine how messages are transported in the organization. This means that the Hub Transport servers in your Exchange organization retrieve information from Active Directory in order to determine how messages should be routed between servers. You need to deploy a Hub Transport server in each site that contains a Mailbox server, such that when user A in one site sends a message to user B in another site, the Mailbox server contacts the Hub Transport server in its own site, and then routes the message to the Hub Transport server in user B’s site, ultimately delivering the message to the mailbox server hosting user B’s mailbox. NOTE All Hub Transport servers use secure SMTP when exchanging messages internally in the organization. They use the industry standard SMTP Transport Layer Security (TLS) so that all traffi c between the Hub Transport servers are authenticated and encrypted. This removes the capability for internal snooping. In addition, all RPC communication between Hub Transport and Mailbox servers is encrypted. I’ve tried to illustrate how messages are routed in a basic Exchange 2007 organization in Figure 6.1. Notice that the Mailbox and Hub Transport servers use RPC as the basis of communication, but that two Hub Transport servers speak SMTP when exchanging messages. Hub Transport Server AD Site 2 Hub Transport Server AD Site 1 Sender Recipient Encrypted RPC Encrypted RPC Mailbox Server Mailbox Server Secure SMTP (TLS) Figure 6.1 Path for Message Sent from a User in One AD Site to a User in Another AD Site 318 Chapter 6 • Managing the Hub Transport Server Role When a Hub Transport server in an AD site establishes an SMTP connection to a Hub Transport server in another AD site, in order to deliver a message, it makes use of round-robin load balancing mechanisms. This means that if the fi rst Hub Transport server contacted doesn’t respond to a connection, it will try to establish an SMTP connection to the next Hub Transport server in the AD site. This makes Hub Transport servers are fault-tolerant out of the box. Since routing is determined from Active Directory sites, the Exchange link state update functionality, used in previous versions of Exchange, has been discontinued. The link state functionality of old was used by each routing group master to update and keep their link state tables current, propagating this information back to the other Exchange Servers in the organization. The use of Active Directory sites in Exchange 2007 creates a more deterministic routing topology. Managing the Hub Transport Server All organizationwide Hub Transport settings are stored in Active Directory. This means that any modifi cations or confi guration settings, except receive connector specifi c settings, are refl ected on all Hub Transport servers in the organization. In the following, we’ll go through each of the tabs available under the Hub Transport subnode shown in Figure 6.2. Since it would be silly to cover the receive connectors in a section of their own, they will be included in this section as well. Remote Domains The fi rst tab is the Remote Domains tab. Here, you can confi gure message transfer settings between Exchange 2007 and external SMTP domains. When you set up a remote domain, you can control mail fl ow with more precision, designate message formatting and policy, and specify acceptable character sets for messages that are sent to, and received from, the remote domain. As you can see in Figure 6.2, there’s a default remote domain entry confi gured after installation of the Hub Transport NOTE When multiple paths exist to a specifi c AD site, a Hub Transport server will use deterministic algorithms to choose one of the available paths. Since one of the paths will always be chosen, the algorithms are deterministic. To read more about AD site and connector selection algorithms used by routing, see the following blog post on the MS Exchange Team blog: http://msexchangeteam.com/archive/2006/09/15/428920.aspx Managing the Hub Transport Server Role • Chapter 6 319 Figure 6.2 Available Tabs under the Hub Transport Node server role. The domain address space is confi gured as *, which represents all external domains. This means the settings confi gured in the remote domain entry are applied to all outbound messages. If you have specifi c requirements for one or more external SMTP domain names, you can confi gure additional remote domain entries as necessary. I’ll show you how a new remote domain entry is created later on, but fi rst let’s take a look at the settings confi gured for the default remote domain entry. When looking at the Properties of the Default Remote Domains entry, you are presented with the General tab, as shown in Figure 6.3. 320 Chapter 6 • Managing the Hub Transport Server Role Figure 6.3 Out-of-Offi ce Message Options Here, we can specify how the Hub Transport server should handle out of offi ce (OOF) messages to the specifi ed SMTP domains in the remote domains entry. We have four options to choose from: ■ Allow none No out-of-offi ce messages will be delivered to the remote domain. ■ Allow external out-of-offi ce messages only Only out-of-offi ce messages confi gured as external using an Outlook 2007 or OWA 2007 client, and where the respective mailbox is stored on an Exchange 2007 Mailbox server, will be delivered to the remote domain. Managing the Hub Transport Server Role • Chapter 6 321 ■ Allow external out-of-offi ce messages, and out-of-offi ce messages set by Outlook 2003 or earlier clients or sent by Exchange Server 2003 or earlier servers Out-of-offi ce messages that are confi gured as external with an Outlook 2007 or OWA 2007 client, and where the respective mailbox is stored on an Exchange 2007 Mailbox server, will be delivered to the remote domain. In addition, out-of-offi ce messages set by Outlook 2003 and earlier, regardless of the server version of their mailbox store, will be delivered to the remote domain. In other words, out-of-offi ce messages that are sent by Exchange 2003 or earlier servers, no matter what client version was used to set the out-of- offi ce message, will be delivered to the remote domain. ■ Allow internal out-of-offi ce messages, and out-of-offi ce messages set by Outlook 2003 or earlier clients or sent by Exchange Server 2003 or earlier servers Only out-of-offi ce messages that are confi gured as external with an Outlook 2007 or OWA 2007 client, and where the respective mailbox is stored on an Exchange 2007 Mailbox server, will be delivered to the remote domain. In addition out-of-offi ce messages that are set by Outlook 2003 and earlier, regardless of the server version of their mailbox store, will be delivered to the remote domain. Out-of-offi ce messages that are sent by Exchange 2003 or earlier servers, no matter what client version was used to set the out-of-offi ce message, will be delivered to the remote domain. The Allow external out-of-offi ce messages only option is selected by default. Let’s continue on to the next tab, the Message Format tab, shown in Figure 6.4. I bet this tab looks familiar to many of you, as it’s very similar to the one we all know from Exchange 2003, although Exchange 2007 offers a few new options. The following is a short description of each option under the Message Format tab: ■ Allow automatic replies This option allows automatic replies to be sent to the remote domain. ■ Allow automatic forward This option will allow automatic forwards to be sent to the remote domain. ■ Allow delivery reports This option allows delivery reports to be sent to all recipients in any remote domain. ■ Allow non-delivery reports This option allows NDRs to be sent to all recipients in any remote domain. ■ Display sender’s name on messages This option allows a user’s display name to be visible to the recipient of the message. ■ Use message text line wrap at column If you want to use line-wrap in message text for outgoing messages, this option should be enabled. When enabled, you must specify the line-wrap size (between 0 and 132 characters). To set the value to unlimited, leave the fi eld blank. . between Exchange 2007 and external SMTP domains. When you set up a remote domain, you can control mail fl ow with more precision, designate message formatting and policy, and specify acceptable. between Hub Transport and Mailbox servers is encrypted. I’ve tried to illustrate how messages are routed in a basic Exchange 2007 organization in Figure 6.1. Notice that the Mailbox and Hub Transport. organization. They use the industry standard SMTP Transport Layer Security (TLS) so that all traffi c between the Hub Transport servers are authenticated and encrypted. This removes the capability