Ryepup gave us a great couple of simple examples for CL-SMTP. Unfortunately when I tried to combine them to send an HTML email that had an attachment, I did not get the expected results. Instead, we insert an inappropriate ContentType header above the multipart then the message body has content type text/plain. I saw Leslie Polzer’s comment about a BKNR branch of cl-smtp that handled mime-types better. So I downloaded it, fired it up, bound the content-type variable and it almost produced the correct email. Unfortunately the result email was missing a newline after the header so my client skipped displaying this first email part (assuming it to be part of the header). I submitted a patch, that was accepted, that adds the newline after the multipart message header.