Hello,Using ESX 3.5 we have installed an Exchange 2007 mailbox/hub transport box on 2008 server.Can anyone make a memory recommendation as far as how much it will take with 650 users?Thanks

Hey, Resource requirement is still same for virtual environment. If it is only Mailbox server, then 2GB + 2-5MB per mailbox and with combination of multiple roles, minimum 4GB + 2-5MB per mailbox. Detail explaination can be found in below article. Planning Memory Configurations -http://technet.microsoft.com/en-us/library/bb738124.aspx Make sure that you are following MS support policy while using VMWare... Microsoft Support Policies and Recommendations for Exchange Servers in Hardware Virtualization Environments -http://technet.microsoft.com/en-us/library/cc794548.aspxAmit Tank | MVP - Exchange | MCITP:EMA MCSA:M | http://ExchangeShare.WordPress.com