Hub Transport

Microsoft Exchange Server 2007 will reach end of support on April 11, 2017. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.


Applies to: Exchange Server 2007, Exchange Server 2007 SP1, Exchange Server 2007 SP2, Exchange Server 2007 SP3

The Microsoft Exchange Server 2007 Hub Transport server role is deployed inside your organization's Active Directory directory service. It handles all mail flow inside the organization, applies organizational message policies, and is responsible for delivering messages to a recipient's mailbox. Hub Transport servers provide the following functionality:

  • Mail flow   The Hub Transport server role processes all mail that is sent inside the Exchange 2007 organization before it is delivered to a recipient's Inbox inside the organization or routed to users outside the organization. There are no exceptions to this behavior.

  • Categorization   The categorizer performs recipient resolution, routing resolution, and content conversion for all messages that move through the Exchange 2007 transport pipeline.

  • Routing   The Hub Transport server role determines the routing path for all messages that are sent and received in the organization.

  • Delivery   Messages are delivered to a recipient's mailbox by the store driver. Messages that are sent by users in your organization are picked up from the sender's Outbox by the store driver and are put in the Submission queue on a Hub Transport server.

Transport Policy and Compliance

Many organizations have legal, regulatory, or internal requirements to filter, process, and store e-mail that is between users in the organization. Additionally, many organizations have additional requirements for how to handle mail sent to or from the Internet. A collection of Transport Policy and Compliance agents in Exchange 2007 helps organizations more easily comply with these legal, regulatory, and internal requirements by providing ways to configure rules and settings that help you meet these requirements.

The following Transport Policy and Compliance agents are available in Exchange 2007 and run on the Hub Transport server role:

  • Transport Rules agent   This agent enables organizations to create rules based on conditions, exceptions, and actions. Conditions apply to users, distribution lists, and message contents. Exceptions let you exclude specific users, distribution lists, or SMTP connectors. Actions define what happens to a message under which conditions and exceptions, including redirecting, returning, sending to an alternative recipient, and deleting the message. Rules that are defined on the Hub Transport server are applied to all users in your organization and to all messages sent and received by users in your organization.

  • Journaling agent   This agent provides your organization with a method of recording some or all e-mail messages that are sent or received by any user in your Exchange 2007 organization. You can scope journal rules to record messages that are sent and received by users inside the same organization, to record messages that are sent to or received from the Internet, or to record any message that passes through a Hub Transport server during transport.

For More Information

For more information, see the following topics: