Example 4 shows this code for creating an HTML email:
Code:
/* To send HTML mail, you can set the Content-type header. */
$headers = "MIME-Version: 1.0\r\n";
$headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
I'm not too sure of the exact usage, tho'. I saw your question and remembered I had run across this while looking into setting up a mail list for a friend the other night. I haven't gotten around to using it yet.