When you install Exchange you are prompted for what modes you want to install. These are listed below. If Gateway server is selected no other option may be chosen. In beta 1 there is only a 32bit version of the Unified Messaging Server.

·                     Bridgehead Server  

·                     Client Access Server.

·                     Gateway Server 

·                     Mailbox Server   

·                     Unified Messaging Server 

The following is copied from the Help file that comes with the
Beta and goes into a bit more depth about what each component does.

Bridgehead Server

The Microsoft® Exchange Server 12 Bridgehead Server Role is deployed inside your organization's Active Directory directory service. It handles all internal mail flow, applies organizational message routing policies, and is responsible for delivering messages to a recipient's mailbox:

·         Mail Flow   The Bridgehead Server Role processes all mail that is sent inside the Exchange Server 12 organization before it is delivered to a recipient's Inbox inside the organization or routed to users outside the organization. There are no exceptions to this behavior.

·         Categorization   The Categorizer performs recipient resolution, routing resolution, and content conversion for all messages that move through the Exchange Server 12 transport pipeline.

·         Routing   The Bridgehead Server Role determines the routing path for all messages that are sent and received in the organization.

·         Delivery   Messages are delivered to a recipient's mailbox by the Store driver. Messages that are sent by users in your organization are picked up from the sender's Outbox by the Store driver and are put in the Submission queue on a bridgehead server.

Message Hygiene

The Exchange Server 12 Bridgehead Server Role can provide the option of having additional layers of spam protection when it is configured to run some or all the following agents that work together to provide different layers of spam filtering and protection:

·         Attachment Filter agent   This agent filters messages based on attachment file name, file name extension, or file MIME content type. You can configure this agent to block a message and its attachment, to strip the attachment and enable the message to pass through, or to silently delete the message and its attachment.

·         Content Filter agent   This agent uses Microsoft SmartScreen technology to assess the contents of a message. The Intelligent Message Filter is based on patented machine learning technology from Microsoft Research. The Intelligent Message Filter learns distinguishing characteristics of legitimate e-mail and of spam. Based on these characteristics, the Intelligent Message Filter helps determine whether an incoming message is spam or legitimate e-mail.

·         Recipient Filter agent   This agent compares the recipients that are identified in the RCPT TO: SMTP header to known recipients who are identified in an IP Block list and to the local recipient directory which stores valid recipients that exist inside the organization to determine what action, if any, to take on a particular message.

·         Sender Filter agent   This agent compares the sender identified in the MAIL FROM: SMTP header to known senders identified in an IP Block list to determine what action, if any, to take on a particular message.

Message Policy

Many organizations have legal, regulatory, or internal requirements to filter, process, and store e-mail that is between users in the organization. Additionally, many organizations have additional requirements for how to handle mail sent to or from the Internet or between partner organizations. A collection of Message Policy agents in Exchange Server 12 helps organizations more easily comply with these legal, regulatory, and internal requirements by providing ways to configure rules and settings that help you meet these requirements. The following Message Policy agents are available in Exchange Server 12:

·                     Address Rewrite agent   This agent enables the modification of the SMTP address for any sender or recipient of messages sent or received by your organization. Address rewriting can be useful in scenarios where an organization wants to hide internal domains, to enable multiple organizations appear as a single organization, or to integrate services that are provided to an organization by a third-party.

·                     Bridgehead Mail Flow Control agent   This agent enables organizations to create rules based on conditions, exceptions, and actions. Conditions apply to users, distribution lists, and message contents. Exceptions let you exclude specific users, distribution lists, or SMTP connectors. Actions define what happens to a message under which conditions and exceptions, including redirecting, returning, sending to an alternative e recipient, and deleting the message. Rules that are defined in the Bridgehead Mail Flow Control agent are applied to all users in your organization and to all messages sent and received by users in your organization.

·                     Disclaimer agent   This agent is not available for this pre-release version of Exchange Server 

·                     Journaling agent   This agent provides your organization with a method of recording some or all e-mail messages that are sent or received by any user in your Exchange Server 12 organization. Journaling can be scoped to record messages that are sent and received by users inside the same organization, to record messages that are sent to or received from the Internet, or to record any message that passes through a bridgehead server during transport.

Client Access Server

The Client Access Server Role supports Microsoft Outlook Web Access and Exchange ActiveSync client applications and POP3, and IMAP4 protocols. The Client Access Server Role also supports services, such as Autodiscovery and Web services.

Gateway Server

The Microsoft® Exchange Server 12 Gateway Server Role is deployed in your organization's perimeter network and handles all Internet-facing mail flow, providing protection against spam, and the encryption and decryption of messages sent between trusted Exchange Server 12 organizations. The Gateway Server Role handles the following scenarios:

·         Mail Flow   The Gateway Server Role accepts mail coming into the Exchange Server 12 organization from the Internet, from trusted Exchange Server 12 gateway servers in external organizations, and in some forest-to-forest scenarios, plus routes all outbound messages to the Internet.

·         SMTP Receive   The Gateway Server Role helps protect the Exchange Server 12 organization from spam by filtering inbound messages as they arrive.

·         Categorization, Routing, and Delivery   The Gateway Server Role routes all accepted messages to a Bridgehead Server Role inside the organization. The Gateway Server Role uses Domain Name System (DNS) to locate servers outside your organization to which outbound messages must be delivered.

Message Hygiene

The Exchange Server "12" Gateway Server Role helps prevent users in your organization from receiving spam by providing a collection of agents that work together to provide different layers of spam filtering and protection:

·         Attachment Filter agent   This agent filters messages based on attachment file name, file name extension, or file MIME content type. You can configure this agent to block a message and its attachment, to strip the attachment and allow the message to pass through, or silently delete the message and its attachment.

·         Connection Filter agent   This agent filters messages based on the IP address of the remote server from which a message is sent. A variety of IP Block lists and IP Allow lists and optional services are used to determine what action, if any, to take on a particular message based on its source IP address.

·         Content Filter agent   This agent uses Microsoft SmartScreen™ technology to assess the contents of a message. The Intelligent Message Filter is based on patented machine learning technology from Microsoft Research. The Intelligent Message Filter learns distinguishing characteristics of legitimate e-mail and of spam. Based on these characteristics, the Intelligent Message Filter helps determine whether an incoming message is spam or legitimate e-mail.

·         Recipient Filter agent   This agent compares the recipients that are identified in the RCPT TO: SMTP header to known recipients identified in an IP Block list and to the local recipient directory which stores valid recipients that exist inside the organization to determine what action, if any, to take on a particular message.

·         Sender Filter agent   This agent compares the sender identified in the MAIL FROM: SMTP header to known senders identified in an IP Block list to determine what action, if any, to take on a particular message.

·         Sender ID agent   This agent relies on the RECEIVED: SMTP header and a query to the sending system's DNS service to determine what action, if any, to take on a particular message.

Message Policy

Many organizations have legal, regulatory, or internal requirements to filter, process, and store e-mail that is between users in the organization. Additionally, many organizations have additional requirements for how to handle mail sent to or from the Internet or between partner organizations. A collection of Message Policy agents in Exchange Server 12 helps organizations more easily comply with these legal, regulatory, and internal requirements by providing ways to configure rules and settings that help you meet these requirements. The following Message Policy agents are available in Exchange Server 12:

·         Address Rewrite agent   This agent enables the modification of the SMTP address for any sender or recipient of messages sent or received by your organization. Address rewriting can be useful in scenarios where an organization wants to hide internal domains, to enable multiple organizations appear as a single organization, or to integrate services that are provided to an organization by a third-party.

·         Disclaimer agent   This agent is not available for this pre-release version of Exchange Server 12.

·         Gateway Mail Flow Control agent   This agent is not available for this pre-release version of Exchange Server 12.

Message Security

Domain security provides an elevated level of e-mail security between two business partners that send mail to and receive mail from each other through the Internet. Additionally, a business-to-business domain security relationship can reduce excessive management overhead that might otherwise be required to provide domain security between two business partners. Domain security enables the following:

·         Message-level encryption and digital signatures   Domain security is enabled when messages are sent using encryption and digital signatures.

·         Ad-hoc business-to-business message security   Domain security is enabled automatically when two potential partners recognize each other.

·         Partner-to-partner   Domain security is enabled explicitly between two partners.

Mailbox Server

The Microsoft Exchange Server 12 Mailbox Server Role hosts mailbox databases. The Mailbox Server Role is required if you plan to host user mailboxes, public folders, or both on the server.

The Mailbox Server Role in Exchange Server 12 integrates with Active Directory directory service better than it did in earlier versions of Exchange. This improved integration improves the deployment experience and operations of an Exchange mailbox server. The Mailbox Server Role has also added improvements to the information worker experience with richer calendering, resource management, and offline address book downloads.

Unified Messaging Server

Exchange Server 12 Unified Messaging integrates Exchange Server with telephony networks and brings the Unified Messaging features to the core of Exchange Server.

Currently, most users and IT departments manage their voice mail and fax messages separately from their e-mail. Voice mail and e-mail exist as separate inboxes hosted on separate servers that are accessed through the desktop for e-mail and through the phone for voice mail. Fax messages are not received into a user's inbox, but are instead received by stand-alone fax machines or to a centralized fax server. Unified Messaging offers an integrated store for all messages, as well as access to content through both the desktop and the phone.

Exchange Server 12 Unified Messaging provides a single point of message administration for Exchange administrators in an organization. The features within Exchange Server 12 Unified Messaging allow an Exchange administrator to:

·         Manage the voice mail, e-mail, and fax systems from a single platform

·         Manage Unified Messaging using scriptable commands

·         Build highly-available and reliable Unified Messaging infrastructures

The Unified Messaging Server Role in Exchange Server 12 allows users to access voice mail, e-mail, fax messages, and calendar information that is located in their Exchange Server 12 mailbox from an e-mail client such as Microsoft® Outlook® or Outlook Web Access, from a Microsoft Exchange ActiveSync® mobile device such as a Windows® SmartPhone or PDA, or simply from a telephone.

Unified Messaging in Exchange Server 12 provides users with features such as:

·         Call Answering   Call answering is the process of answering an incoming call on behalf of a user, playing their personal greeting, recording a message, and submitting it for delivery to their inbox as an e-mail message.

·         Fax Receiving   Fax receiving is the process of submitting a fax message for delivery to the Inbox. The fax receiving feature gives users the ability to receive fax messages in their Inbox.

·         Subscriber Access   The subscriber access feature allows dial-in access for company users. Company users or subscribers who are dialing into the Unified Messaging system can access their mailbox using Outlook Voice Access. Subscribers who use Outlook Voice Access can access the Unified Messaging system using either touch tone or voice inputs.

Using a telephone, a subscriber or user can:

·         Access voice mail over a telephone.

·         Listen, forward, or reply to e-mail messages over a telephone.

·         Listen to calendar information over a telephone.

·         Access or dial contacts stored in the global address list or a personal contact list over a telephone.

·         Accept or cancel meeting requests over a telephone.

·         Set a voice mail out-of-office message.

·         Set user security preferences and personal options.

• Auto-Attendant   An auto attendant is a set of voice prompts that allows external users to have access to the Exchange Server 12 Unified Messaging system. Auto attendants can allow the user to use either DTMF or "touch tone" and speech inputs to navigate the menu structure, place a call to a user, or locate a user and then place a call to that user. An auto attendant gives the administrator the ability to:
• Create a customizable set of menus for external users.
• Define informational greetings, business hours greetings, and non-business hours greetings.
• Define holiday schedules.
• Describe how to search the organization's directory.
• Describe how to connect to a user's extension so external callers can call a user by specifying their extension.
• Describe how to search the organization's directory so external callers can search the organization's directory, and call a specific user.
• Allow external users to call the operator.