Can someone provide details on the default permissions on Exchange 2003 mailboxes. I have just started at a new company and the permissions are a mess. I want to clean them up and start over but want to make sure that the default out -of-the-box permissions are reset before continuing. I obviously dont want to remove permissions and then find that users cannot access their mailboxes. When I look under the Security tab on the company's properties in Exchange System Manager, permissions are being inherited from somewhere, which appears to me to be giving pretty much full control to domain administrators and enterprise admins. Where are these permissions being inhertied from ? Do they need to be there ?

Software/Hardware used:
Exchange server 2003