Are there site-specific error conditions that should be optimized for in the monitoring phase?

Will automatic fail-over be allowed, or should administrator notification be the first recovery action?

Which e-mail clients must be protected during fail-over? What access methods do they use? And how will these be migrated to the disaster recovery site during recovery?

With these requirements documented, you begin design. The choice of a disaster-recovery site should be the first decision you make. While some organizations decide to use remote corporate offices as backup locations, many look to collocated hosting centers that provide full redundancy for power and network connectivity. If you're using a remote office location, understand that it probably won't be possible to piggyback the replication traffic required for the mail store and log file mirrors onto the existing cross-site network traffic. An analysis of bandwidth requirements and availability must be done. Designing a sufficient connection between the sites -- one that offers sufficient bandwidth and takes latency into account -- is critical to the success of the deployment.

At this stage, you should also identify and document the servers, the storage capacity and configuration, the network routing between the primary site and the disaster-recovery site, and the method of client redirection that will be used.