Background Information

Exchange Server 2007 is an e-mail system that consists of five roles. Together these roles form an “Exchange Server organization.” You should have one Exchange Server organization, even if you have multiple instances of some roles installed. This is different from previous versions of Exchange Server, which had only two parts, a “front end” (roughly equivalent to client access role), and a “back end” (roughly equivalent to edge transport, hub transport, and mailbox roles).

Role Explanation

Client access

Runs Outlook Web Access (OWA), Exchange ActiveSync® for client applications, POP3, IMAP4, Autodiscover Service, and Web Services.

Edge transport

Handles e-mail that is flowing outside of your company (SMTP and smart host services), and relays mail to hub transport for delivery inside your company.

Hub transport

Handles e-mail flow within your company, and relays mail to edge transport for delivery outside your company.


Hosts users’ mailboxes and public folders.

Unified Messaging (not present in Windows EBS)

Adds voice messaging, fax, and e-mail-over-telephone features.

For more background knowledge, see the Additional References later in this document.

Background knowledge specific to Windows Essential Business Server

Components of Exchange Server are installed on the Windows EBS Messaging Server and Security Server:

  • Messaging Server runs the client access, hub transport, and mailbox roles.

  • Security Server runs the edge transport role.

The Windows EBS Installation Wizard detects if you have an existing Exchange Server organization. If an existing organization is found, it installs and configures Exchange Server 2007 to integrate with your organization, including automatically creating routing group connectors between your existing Exchange Servers and the Messaging Server to ensure that the mail flow is not interrupted.