Users gain access to mailboxes in different ways:
Users log on and use their mailboxes as normal. Logically, Exchange calls this owner access.
An administrator can delegate full access to a mailbox to another user. See Chapter 6, “More about the Exchange Administration Center,” for more information on this topic. This is called delegate access. Users can also grant access through Outlook to individual folders in their mailbox such as the calendar or the Inbox.
Administrators can grant themselves access to a user’s mailbox and then log on to it. This is equivalent to delegating access because the same type of permissions are used to open and work with mailbox data.
Administrators can run operations against a mailbox that can ...