Overview

Earlier versions of Exchange did not scale well enough, at a low enough cost per mailbox (because of expensive hardware and recovery options) to allow IT administrators the ability to match the ever increasing mailbox sizes of personal e-mail accounts. Exchange 2007 offers dramatic performance and scalability improvements when compared to prior versions of Exchange. Long recovery times have been a significant impediment to the adoption of larger mailbox sizes. The introduction of cluster continuous replication (CCR) offers the ability to rapidly recover from outages at a low cost. These performance and rapid recovery improvements enable IT departments to deploy large mailboxes easily and at a low cost. Increased mailbox sizes improve end-user productivity and satisfaction, reduce IT administrative costs, improve security, and help meet business and regulatory compliance requirements.  For more information on the end user and IT benefits that are available by deploying large mailboxes in Exchange 2007, please see the whitepaper, Planning for Large Mailboxes with Exchange 2007.

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http://msexchangeteam.com/archive/2008/11/04/450039.aspx