One of the primary new concepts introduced in Exchange 2007 is that of server roles. Instead of one generic installation of Exchange Server, you can now choose from several different roles. These roles are designed to logically group the features that are required to accomplish a set of tasks. The Exchange 2007 server roles are as follows: 

• Mailbox   The Mailbox server role is responsible for hosting mailbox and public folder databases. A mailbox database contains the users' mailboxes.
  
  
• Client Access   The Client Access server role enables mailbox access through Microsoft Office Outlook Web Access, Post Office Protocol version 3 (POP3), Internet Message Access Protocol version 4rev1 (IMAP4), Outlook Anywhere (formerly known as RPC over HTTP), and Exchange Server ActiveSync.
  
  
• Hub Transport   The Hub Transport server role handles routing by using Microsoft Active Directory sites and site topology. The Hub Transport server also applies policies to incoming and outgoing mail.
  
  
• Unified Messaging   Unified Messaging (UM) combines voice messaging, fax, and e-mail messaging into a single messaging infrastructure that can be accessed from a telephone and a computer.
  
  
• Edge Transport   The Edge Transport server role provides antivirus and anti-spam protection in a perimeter network for the Exchange organization.
  
  

Exchange 2007 introduces a new management tool for administrators. The Exchange Management Shell is a command-line interface that resembles other command-line interfaces, such as the Microsoft Windows Script Host. Administrators can manage every aspect of Exchange 2007, from creating new e-mail accounts to disabling a user's mobile device.

Two Exchange 2007 features use continuous replication. Asynchronous replication technology is used to create a copy of a storage group and keep the copy current through log shipping and replay. Through continuous replication, the log files of a production database are applied to a copy of that database. The two Exchange 2007 features that use this technology are local continuous replication (LCR) and cluster continuous replication (CCR).

• Local continuous replication   LCR lowers the total cost of ownership for Exchange 2007 by reducing the number of regular backups that are required for data protection. LCR does not eliminate the need to create backups, because data backups are important if a disaster strikes. However, it does significantly reduce the need to create regular, daily backups. LCR provides fast recovery with current data, and also a single-server solution for copying and replaying transaction logs.
  
  
• Cluster continuous replication   CCR combines automatic management of redundancy and data replication at the application level. CCR can be deployed without a single point of failure in a single data center or between two data centers. Transaction log replication is used to copy the databases and keep data current among cluster nodes. The scheduled outage functionality in CCR is designed to make sure that all log data on the active node is successfully copied to the passive node. Therefore, scheduled outages do not result in loss of data, even though replication occurs asynchronously.
  
  

For more information about the concepts in this topic, see the following topics:

• Client Access Server Role: Overview
  
  
• Edge Transport Server Role: Overview
  
  
• Hub Transport Server Role: Overview
  
  
• Mailbox Server Role: Overview
  
  
• Unified Messaging Server Role: Overview
  
  
• Using the Exchange Management Shell
  
  
• Managing Local Continuous Replication
  
  
• Managing Cluster Continuous Replication