I have read that microsoft states that you 3 admins for installation of exchange on the forest prep. Schema admin & Enterprise Admin & local/domain admin If a user is installing it as an Enterprise Admin group why would he or she need a domain/local admin group Surly the enterprise admin group is the highest user group in a forest

It does not require those groups to actually do the install. It requires those groups to extend the schema and prep the forest and domain. There are three prepatory commands that get run before the install starts. setup /PrepareSchema setup /PrepareAD setup /Preparedomain (or Alldomains) Each of the above switches requires different membership to the "big 3" groups. These switches only need to be run once (not for every install of an Exchange server). See link: http://technet.microsoft.com/en-us/library/bb125224.aspx These require special permissions to create and modify the objects that it needs. If you want to install Exchange without being a member of those groups, then you can provision Exchange server for Delegated Setup. Note that you cannot delegate out installing the first instance of Exchange in an org. See this link for more info: http://technet.microsoft.com/en-us/library/bb201741.aspx Tim Harrington - Catapult Systems - http://HowDoUC.blogspot.com