Exchange 2007 SP1 includes the following enhancements to core transport functionality:

• Back pressure   Back pressure is a system resource monitoring feature for the Hub Transport server role and the Edge Transport server role. This feature enables the Hub Transport servers and Edge Transport servers to respond to high resource use. In Exchange 2007 SP1, the free disk space requirement has changed from 4 GB to 500 MB. For more information, see Understanding Back Pressure.
  
• Additional configuration options in the Exchange Management Console   In Exchange 2007 SP1, you can configure more transport feature settings in the Exchange Management Console. For more information, see Configuring Transport Server Properties.
  

Exchange 2007 SP1 includes the following enhancements to message processing and routing functionality on the Hub Transport server role:

• Priority queuing   The message priority that is assigned to a message by an Outlook user is now considered by the categorizer. This helps ensure that messages sent with high importance receive priority handling and are delivered more quickly than messages with a low importance setting. For more information, see Understanding Priority Queuing in Exchange 2007 SP1.
  
• Active Directory site links   The Set-AdSiteLink cmdlet is used to configure Exchange-specific settings on an Active Directory site link. In Exchange 2007 SP1, the Set-AdSiteLink cmdlet includes the MaxMessageSize parameter. This parameter lets the administrator restrict the maximum message size for messages that are relayed between Active Directory directory service sites.
  
• Routing group connectors   When Exchange 2007 coexists with Microsoft Exchange Server 2003 or Exchange 2000 Server, routing group connectors are used to relay messages between the Exchange 2007 routing group and legacy routing groups. In Exchange 2007 SP1, the New-RoutingGroupConnector cmdlet and the Set-RoutingGroupConnector cmdlet include the MaxMessageSize parameter. This parameter lets the administrator restrict the maximum message size for messages that are relayed between Exchange 2007 Hub Transport servers and Exchange 2003 or Exchange 2007 bridgehead servers.
  
• Send connector configuration   In Exchange 2007 SP1, the scoping of a Send connector to a single Active Directory site is simplified by the addition of the IsScopedConnector parameter in Exchange Management Shell cmdlets and the Scoped send connector check box in the Exchange Management Console. When a Send connector is scoped, only the Hub Transport servers in the same Active Directory site as the Send connector's source servers consider that Send connector in routing decisions.
  
• AD RMS Prelicensing agent   Exchange 2007 SP1 includes the AD RMS Prelicensing agent. You can enable this Windows Rights Management Services (RMS) agent on the Hub Transport server to provide better functionality for letting Outlook users access protected messages. For more information, see Managing the AD RMS Prelicensing Agent.
  
• X.400 authoritative domains   Exchange 2007 SP1 provides support for configuring an X.400 address space as an authoritative domain and also provides support for X.400 long addresses. For more information, see Exchange 2007 SP1 Support for X.400 Authoritative Domains.
  
• Transport rules   Exchange 2007 SP1 enables transport rules to act on Unified Messaging messages, such as voice mail, fax messages, and missed call notifications. For more information about transport rules, see Overview of Transport Rules.
  

Exchange 2007 SP1 includes the following enhancements to the Edge Transport server role:

EdgeSync Synchronization

Cloned Configuration