    # File app/mailsender/mail_sender.rb, line 63
            def add_attachment(file_path)
                    filename = File.basename(file_path)
                    attachment_data = File.open(file_path, "rb").read
                    encoded_attachment = [attachment_data].pack('m')
                    @content << "--#{BOUNDARY}\n"
                    @content << "Content-Type: application/octet-stream; name=\"#{filename}\"\n"
                    @content << "Content-Disposition: attachment; filename=\"#{filename}\"\n"
                    @content << "Content-Transfer-Encoding: base64\n"
                    @content << "\n"
                    @content << "#{encoded_attachment}\n"
            end