Not trying to step on any toes here...
We offer a Cloud-Based Microsoft Hosted Exchange service as well.
We are not resellers.
We manage our own dedicated geo-redundant Enterprise Class Microsoft Exchange Servers with unlimited number of licenses (accounts). Many of our competitors are limited to 20 accounts per domain. Most of our clients have between 500 and 1000 accounts each.
We also provide the latest and full version of Microsoft Exchange... not just OWA. But if you are a road warrior and only need / want OWA - you get that as well.
Our network is HIPAA compliant, fully SSL encrypted, rides on multiple 10gb tier 1 backbones, and is Certified SSAE 16 Type 2 for medical and legal data
--- and again, geo-redundant. If a disaster hits one of our data centers - our servers will automatically switch and pull from redundant servers located in different regions of the U.S. --- Business does not stop.
Most of our clients are hospitals, nursing homes, physicians, and attorneys... Though we are moving heavily into the small business arena. (1 to 25 employees).
As for Spam. We manage our own dedicated Enterprise Class Barracuda servers.