Microsoft Exchange 2007 elaburates a complete new roleset, replacing well-known server roles. Instead we can now install E2x7 with the appropiate role, this includes among all, a smtp server in the DMZ with no Active Directory. Finally Microsoft developed a synchronization tool between ADAM and ADSI.
There are 5 roles in E2x7:
CAS – Client Access Server
This is what has become the replacement of any frontend server. This includes HTTP/RPC, OWA, OMA but for some reason not the new OVA.
BackEnd – Mailbox Server
The old backend server role is not replaced, so this will hold any store.
Bridge – Hub Transport
Handles all mail flow, transport agents and such. Also integrations for other calendars, mailserver etc. will be handled here.
A success to the Exchange product familiy. This will enable us to place a SMTP server in any DMZ, and use this a common gateway in a secure manner. I cannot be installed with the other Exchange features, and includes a ADAM store which it replicates with the AD.
OH MY GOD! – Unified Messaging
I can't tell you this enough – unified messagning has only just begun. The new UM server includes OVA, a new entry point for you email which collaborates with Microsoft Speech Server, enabling a simple phone call to your mailbox.
In the future we will se a merge of Live Communication Server and the UM server role, and because of this, the role is dedicated to its own serverrole. Early this year, Microsoft and Cisco signed an agreement enabling amoung others, CCM and CCME to integrate with Live Communication Server, and therefore also UM.