# File lib/sup/util.rb, line 72
    def self.make_attachment payload, mime_type, encoding, filename
      a = Message.new
      a.header.add "Content-Disposition", "attachment; filename=#{filename.inspect}"
      a.header.add "Content-Type", "#{mime_type}; name=#{filename.inspect}"
      a.header.add "Content-Transfer-Encoding", encoding if encoding
      a.body =
        case encoding
        when "base64"
          [payload].pack "m"
        when "quoted-printable"
          [payload].pack "M"
        when "7bit", "8bit", nil
          payload
        else
          raise EncodingUnsupportedError, encoding.inspect
        end
      a
    end