d using
        the utf-8 charset and a language of ''.

        Examples:

        msg.add_header('content-disposition', 'attachment', filename='bud.gif')
        msg.add_header('content-disposition', 'attachment',
                       filename=('utf-8', '', Fußballer.ppt'))
        msg.add_header('content-disposition', 'attachment',
                       filename='Fußballer.ppt'))
        NÚ