This procedure can be used to disable client access to a
specified user's mailbox. The mailbox can still receive mail if its
quota has not been exceeded. The procedure sets the following
mailbox attributes to false:
Important Note: The state of these settings prior to the
call is not persisted in any way. When EnableMailbox is called, the
settings defined in the user's mailbox plan are applied.
The caller must be at least a member of role: UserCreators.