There are five server roles in Exchange Server 2007:
- Mailbox: Hosts mailbox databases, which contain user mailboxes and public folders.
- Client Access: Allows browser-based, remote, and mobile clients to communicate with Exchange Server through Outlook Anywhere (RPC/HTTP), Outlook Web Access, ActiveSync, POP3, or IMAP4.
- Hub Transport: Provides message transport services within the organization. All messages flow through the hub transport, allowing organization-wide enforcement of policies.
- Unified Messaging: Provides telephony capabilities including voice mail, fax receiving, automated attendant, and Outlook Voice Access.
- Edge Transport: Serves as an e-mail gateway, helping to block spam and viruses at the network perimeter before they reach internal mail servers.