Some thoughts: On May 24, 2011, at 18:52 , Amancio Díaz Suárez wrote: > {ok, PngContent0} = file:read_file(?MAIL_PNG_LOGO), > PngContent1 = base64:encode(PngContent0), > PngContent = erlang:binary_to_list(PngContent1), Are you sure that you need to build a List ?