Microsoft® Exchange Server 2007 RTM (Release to Manufacturing) introduced new mailbox availability options like Local Continuous Replication (LCR) and Cluster Continuous Replication (CCR) as compared to Exchange Server 2003 which was limited to the shared storage clustering based on Microsoft Cluster Services. The new release of Exchange Server 2007 Service Pack 1 (SP1) complements Exchange Server 2007 by enhancing the operational performance of high availability features, adding disaster recovery options and adding support for Windows Server® 2008. This article will discuss the Exchange Server 2007 RTM and SP1 high availability features and associated benefits. Performance analysis conducted at Dell labs to characterize the behavior of new high availability options and improvements will also be discussed.