Unified Messaging

This server hosts the integration of voice (voice-mail), calendar, email and fax.  Unified messaging enables voicemail and faxes to be delivered to the Outlook 2010 (Version 14) Inbox.  This role needs 'speechify', which most likely the wizard will install automatically.

Edge Transport or Gateway Server

This Edge Transport (Gateway) server is a new development for Microsoft's Exchange.  You should think of the Gateway server as the hygiene serve.  Consider it as a rival of Message Labs or as a replacement for your third party email cleaning service.  An absolute requirement is that the Edge server must be in its own workgroup and must not, repeat not, be a member of the Exchange Organization's Active Directory domain.  For this reason the Role Selection wizard displays a horizontal separator between this and the other server roles.

For a variety of reasons the Edge server has proved to be the least popular Exchange Server 2010 role.  This is especially true in the U.K. where people rely on other solutions to clean mail and act as a gateway to the internet. 

Exchange Server 2010 Two Editions - Standard and Enterprise

Exchange Server 2010 is available in two editions; Standard and Enterprise.  The difference is determined by the product key.  The Enterprise Edition supports up to 100 databases on each server, whereas the Standard Edition supports only five databases.  Fortunately, Exchange 2010 has no software limit on the database storage, so each storage group database can be as big as you like.  In Exchange 2003 Standard edition, the limit was 16 gigabytesB or 75GB.

Exchange licensing can either be per server or per CAL (Client Access License).  If you find it difficult to work out the cheapest licensing option, check here to see the best solution for your Exchange Organization.

Summary of Exchange Server Roles

Microsoft has decided on a structured approach by providing five roles for Exchange Server.  You have the flexibility of multiple roles on the same server, or you could deploy a dedicated server for each role.  However, remember that the Edge Server MUST be on a separate server in a separate workgroup.  Lastly,  there are advantages in separating the Mailbox and Client Access roles.