| Called When | dkim_close() is called shutting down the application.  It
    deallocates all allocated resources having to do with the DKIM library. 
    It does not deallocate resources associated with any existing
    DKIM handles.  Those must be cleaned
    up first with calls to dkim_free().
    Failure to do so will almost certainly cause application failure when
    those handles are used later, even if only to pass them to
    dkim_free().
     |