For most organizations around the world, e-mail is their top mission-critical service. Throughout nearly 20 years of Exchange development, Microsoft has been improving the Exchange platform, making it more user-friendly and reliable with each release. From Windows clusters to Cluster Continuous Replication to Database Availability Groups and much more, the progress of Exchange in terms of availability and resilience is extraordinary.

In this chapter, we will look at the definitions of availability and resilience, as well as the new architecture of Exchange 2013.