Mailbox SERVER: This server hosts mailboxes and public folders.

Client ACCESS Server: This is the server that hosts the client protocols, such as POP3, IMAP4, HTTPS, Outlook Anywhere, Availability service and Autodiscover service. The Client Access Server also hosts Web services.

Unified Messaging Server: This is the server that connects a Private BRANCH eXchange (PBX) system to Exchange 2010.

Hub Transport Server: This is the MAIL routing server that routes mail within the Exchange organization.

Edge Transport Server: This is the mail routing server that typically sits at the perimeter of the topology and routes mail in to and out of the Exchange organization.

Mailbox Server: This server hosts mailboxes and public folders.

Client Access Server: This is the server that hosts the client protocols, such as POP3, IMAP4, HTTPS, Outlook Anywhere, Availability service and Autodiscover service. The Client Access Server also hosts Web services.

Unified Messaging Server: This is the server that connects a Private Branch eXchange (PBX) system to Exchange 2010.

Hub Transport Server: This is the mail routing server that routes mail within the Exchange organization.

Edge Transport Server: This is the mail routing server that typically sits at the perimeter of the topology and routes mail in to and out of the Exchange organization.