The interest in Exchange 2000 Server for the application service provider (ASP) market seems to be increasing. Many ISP/ASP businesses have offered hosted Exchange services, but they have done so using Exchange 5.5. Exchange 2000 promises better scalability, management, and lower total cost of ownership (TCO) than Exchange 5.5 offers in these hosted environments.

In a hosted environment, a service provider has two architecture choices for offering Exchange services: dedicated or shared. In a dedicated architecture, the service provider must dedicate a separate Exchange organization (and server) to each new customer. This approach creates many challenges when a service provider tries to provide Exchange services at the lowest possible per-seat cost to customers. A dedicated server and organization for each customer means high management overhead, unattainable economies of scale, and limited scalability. Unfortunately for service providers, Exchange 5.5 doesn't lend itself to anything but a dedicated deployment model.

When deploying a shared architecture (made feasible by Exchange 2000), service providers can deploy an overall services infrastructure and configure capacity on demand as they add new customers. A shared architecture eases the management burden and lowers TCO by increasing the economies of scale. As a result, service providers can offer more competitive per-seat prices.

ASPs such as US Internetworking, Data Return, United Messaging have been offering hosted Exchange services for some time. Most offerings included either hosted Messaging API (MAPI) access (using Outlook 2000, 98, or 97) or Outlook Web Access (OWA). However, most ASPs offer these services using the dedicated architecture model. Exchange 2000 brings hope to these service providers with new technologies, architecture, management flexibility, and the option of a shared deployment model that wasn't feasible with Exchange 5.5. Exchange 2000 features such as multiple storage groups (SGs) and databases, the Active Directory (AD), native Internet protocol support, active/active clustering, and a front-end/back-end architecture are much better suited to the needs of service providers that offer hosted messaging services.

Most ASPs I've talked to are anxious to move to a shared architecture model for hosting Exchange because it will let them be more competitive in a market where cost per seat is key. Many service providers are also looking to new models such as offering Exchange services via Terminal Services (Windows Terminal Services, Citrix, WinCenter, WindD), allowing even more architecture choices. As Exchange 2000 becomes a core technology for offering hosted messaging services, we'll learn much more about how Microsoft built this product with more in mind than just your basic corporate messaging deployment.