Exchange 2007 Server Roles – Exchange 2007 has expanded the concept in Exchange 2007 Server of server roles, which further extends the old 2 role front end back end topology, with a new 5 role model.

Breaking down the Exchange 2007 server roles has a lot of advantages, allowing your exchange topology to be more flexible, highly scalable, allowing better hardware utilization, this together with the advantages of 64bit allow more mailboxes to be hosted on a single server.

The five Exchange 2007 Server Roles are as follows and shown in figure 1 below:

·         Mailbox Server Role

·         Client Access Server (CAS) role

·         Hub Transport Server (HTS) role

·         Edge Transport role

·         Unified Messaging

Figure 1 "Exchange 2007 Server Roles"

Each of these Exchange 2007 Server Roles are detailed below

Exchange 2007 Mailbox Server Role

The Exchange 2007 Mailbox server role is responsible for hosting exchange mailboxes and public folders. Given that this is the only function a server with this role will do (Unless installed with multiple roles) along with the 64bit factor the number of mailboxes supported per server is greatly increased.

Exchange 2007 Client Access Server Role CAS

The Exchange 2007 Client Access Server role allows client applications and devices to connect and could be considered the same as the old Exchange front end server, also providing the Outlook Web Access OWA feature. Types of clients that connect to exchange via the Client Access Server Role include:

·         Outlook 2000/2003/2007

·         Via Web browser (OWA)

·         ActiveSync via Mobile Clients Windows Mobile 5 & 6 + other licensed Devices

·         Outlook Express, POP3, IMAP4

Exchange 2007 Hub Transport Server Role HTS

The Exchange 2007 Hub Transport Server role should be considered the co-ordinator of internal mail thru your exchange Organization, and is also responsible for receiving messages from the Edge Transport server for delivery to the internal mailbox servers, and the receiving of messages from Exchange mailbox servers to be sent to the Hub Transport server for delivery to the internet.

Other functions the Hub Transport servers does or can have is:

·         Messaging Policy, Compliance, and retention

Allows rules and setting to be applied to messages as they enter pass thru the Hub transport server role to/from the Mailbox Edge.

Depending on your organization industry and the countries/s you operate in they may be subject to regulations such as Sarbanes Oxley, also your company may have internal policies, the Hub Transport Server is the server where compliance and retention rules are set and acted.

·         Anti-Virus & Anti-Spam features

Your Exchange 2007 Hub Transport server can be configured to perform additional Anti-Virus and Anti-Spam protection, before messages reach your mailbox server. This feature is not enabled on a Hub Transport Server by default and is normally done at the Edge Server level therefore this needs to be enabled if required by your organization at this level.

Exchange 2007 Edge Transport Server Role

A hosting the Exchange 2007 Edge Transport role sits in your organization’s perimeter network (DMZ) and is located on a standalone non-member server (not  a domain member server).  Instead Active Directory Application Mode (ADAM) is used to perform the edgeSync to keep your organizations AD recipient information up to date for recipient filtering.

The primary reason the Edge transport role sits in your perimeter network is for security ensuring messages that enter and leave your organization are legitimate and clean, ensuring security, reducing Spam, and decreasing the number of messages your internal exchange servers need to deal with.

 Sitting in your perimeter network and not on the domain, there is an added security if the server is compromised there is less of a chance of compromising your internal network.

Primary functions performed by the Exchange 2007 Edge Transport Server include:

·         Internet Mail Flow – accepts and sends messages destined for the internet

·         Anti-Spam Anti-Virus – Filter messages before they enter or leave your Exchange org

·         Edge Transport Rules – Taking action on messages that meet specific conditions

·         Address Rewriting – Rewrite SMTP address of internet and external bound messages

Exchange 2007 Unified Messaging Server Role

The Exchange 2007 Unified Messaging Server role is the biggest changes to Exchange 2007, introducing the totally new concept of Voice messaging, other voice features, and faxing to Exchange.

Unified messages features provided by the Exchange 2008 Unified Messaging Server role include:

·         Auto Attendant – A Set of voice prompts that gives external users access to the Exchange 2007 Unified Messaging system

·          telephone, including creating greetings, changing their Unified messaging settings

·         Receiving of Faxes – For delivery to a user/s mailbox

·         Call Answering – Answering of incoming calls for a user

·         Subscriber Access – Gives users access to their mailbox, and unified messaging system via a touchtone telephone.

Exchange 2007 Server roles is one of the biggest changes to Exchange 2007 from previous versions, further segmenting roles improves performance, extends security and scalability, making it the number 1 enterprise messaging platform.