| Exchange Server 2010 implementations have | | | | connected to the Client Access server to check |
| three layers in their architecture: a network layer, | | | | mail. Remote users can check their mail over the |
| directory layer, and messaging layer. The | | | | Internet by using Outlook Anywhere, Outlook |
| messaging layer is where you define and deploy | | | | Web App, Exchange ActiveSync, POP3, or IMAP4, |
| the Exchange Server roles. The Exchange servers | | | | Unified Messaging Server is a middle-tier server |
| at the core of the messaging layer can operate in | | | | that connects a private branch exchange (PBX) |
| the following roles: | | | | system with Exchange Server 2010, that allow |
| Mailbox Server is a back-end server that hosts | | | | voice messages and faxes to be stored with |
| mailboxes, public folders, and their messaging data, | | | | e-mail in a user's mailbox. It also supports call with |
| such as address lists, and meeting items. | | | | automated greetings and message recording, fax |
| Client Access Server accepts Exchange Server | | | | receiving, and dial-in access. With dial-in access, |
| connections from a variety of clients. This server | | | | users can use Outlook Voice Access to check |
| hosts the protocols used by all clients when | | | | voice mail, e-mail, and calendar information; to |
| checking messages. On the local network, | | | | review or dial contacts; and to configure |
| Microsoft Outlook MAPI clients are directly | | | | preferences and personal options. |