We currently are running two CCR (continuous cluster replication) Exchange 2007 servers on Server 2008 R2. We also use mail-enabled public folders. We would like to upgrade to Exchange 2010 so we can lose the external Hub Transport / Client Access server, which I see as one additional point of failure. The problem is the new architecture of Exchange 2010 does not use CCR and its "successor," DAG (database availability group) does not work with public folders. I assume this is part of Microsoft's continuing effort to force everyone onto Sharepoint. Anyway, the question is what would be the best configuration that would let me upgrade to Exchange 2010, keep my mail-enabled public folders and accommodate some form of high availability?