Hosted Exchange: Can it Work for You?

Posted by admin on March 6, 2010 under Help | Be the First to Comment

You don’t have the time, money or manpower to run your own messaging environment, it may be time to consider hosted Exchange

I’ve decided to join Gold’s Gym. With the high upfront costs of fitness equipment, I figured this was a cheaper and better solution than trying to go it alone. Gold’s experienced certified personal trainers are helping me design and implement a fitness plan. With their support, I’m reaching my goal. But if the service ever goes south, I can always leave, because I have the pay-as-you-go plan.

The Gold’s Gym approach isn’t all that different from a hosted Exchange service provider. At the fitness center, as in the data center, you’ll find some expensive hardware. This is why it quickly becomes all about selling gym memberships or Exchange seats—that expensive hardware is a fixed cost. As is the case at Gold’s Gym, hosted Exchange service providers normally employ experienced Microsoft Certified Professionals to help their customers. And similar to how Gold’s Gym offers free weekly passes, hosted Exchange service providers offer free monthly trials.

Having spent the past four years in the hosted Exchange world, I’ve seen how it can provide a compelling benefit to small, medium and even some large enterprises.

What is Hosted Exchange?
Hosted Exchange is a fully managed service—designed, implemented and supported by a service provider. Although it’s rarely differentiated, there are two offerings: multi-tenant, also known as shared hosted Exchange, and single-tenant, also known as dedicated hosted Exchange. For this article, I’ll focus on the much more common multi-tenant offering, where two or more isolated tenants (customers) share the same Active Directory and Exchange infrastructure.

Typically, shared hosted Exchange solutions are large-scale and highly centralized. In addition, they’re built on a high-performance, high-availability infrastructure (hardware-based load balancers and SSL accelerators, redundant routers and switches, redundant servers, and Storage Area Networks). AD is deployed in a single forest, single domain, and single site configuration with an Organizational Unit (OU) assigned to each tenant. For redundancy, at least two Global Catalog servers and at least two Exchange front-end servers are deployed. All Exchange back-end servers are Exchange virtual servers, clustered.

Exchange is deployed in a single Organization with a Recipient Policy, Global Address List, Address List, Offline Address List and a top-level public folder within the root public folder tree, assigned per tenant.

Isolation from other tenants is achieved with Security Groups and Access Control Lists, and by stamping rarely used attributes. For example, the msExchQueryBaseDN attribute on all user objects in a tenant is set to the distinguishedName attribute of its assigned OU. This limits Outlook Web Access-based Address List searches to the members of their OU. Nearly all shared hosted Exchange solutions are deployed with a service management system. This system—typically a Web portal—gives end users, customer administrators, resellers and the wholesaler a central point of access to provision and administer the service.

Finally, hosted Exchange service providers claim their service is cheaper and better than what could be built and maintained in-house. They argue that your total cost is reduced because you share the same infrastructure and applications with other tenants. At the same time, reliability, security and scalability is improved because the service is handled by folks whose core business is designing, implementing and supporting Exchange.

Why Hosted Exchange?
In addition to the “better and cheaper” claim, which all outsourcers tout, two factors are making hosted Exchange a legitimate option for many small, medium and even large enterprises.

* The market is maturing. The role and value of a hosted Exchange service provider is better understood now than it was four years ago when Exchange 2000 first shipped. And if you’re facing a decision on whether to upgrade your existing messaging systems to Exchange 2003, you may never find a better time to consider the hosted option.
* The technology is getting better. Perhaps the most apparent technology improvement is the ability to connect to Exchange servers over the Internet with RPC over HTTPS using Outlook 2003. Prior to this, service providers published MAPI with ISA Servers, deployed VPNs, or ran with fixed RPC ports. RPC over HTTPS finally delivers an efficient standard for the industry. When published through ISA, it truly provides secure Exchange access over the Internet.

Hosted Exchange also benefits from the native mobility features within Exchange 2003. The features are a significant improvement over deploying Exchange 2000 with Mobile Information Server, a step some providers took to offer mobility with Exchange 2000. Full access to e-mail, calendar and contacts through Server ActiveSync and Outlook Mobile Access on a Windows Mobile Pocket PC Phone or a Smartphone is hard to overlook.
In addition, Outlook Web Access for Exchange 2003 offers the ability to create custom OWA Themes, giving providers an opportunity to further brand their service offering. The ability to modify the appearance and the functionality of OWA by using segmentation was available in Exchange 2000; but now, with the improvements in OWA such as forms-based authentication with HTTP compression, customizable logon page, and Spell-check, it’s worth the effort.