--$boundary
Content-Type: multipart/alternative; boundary=\"$boundary2\"

--$boundary2
Content-Type: text/plain; charset="..."
Content-Transfer-Encoding: quoted-printable

txt goes here

--$boundary2
Content-Type: text/html; charset="..."
Content-Transfer-Encoding: quoted-printable

html goes here

--$boundary2--

--$boundary--

##</code><code>##

content-type: multipart/mixed; boundary=\"$boundary\"