This code generates an email. When this email is viewed in Windows Live Hotmail it spits out the code itself not the html content.
$to = "firstname.lastname@example.org";
$subject = "PUT_SUBJECT_HERE";
$mail_body = '
Put HTML content here with variables from PHP if you like
Variable display Example: ' . $subject . '
$headers = "From:email@example.com";
$headers .= "Content-type: text/htmlrn";
mail($to, $subject, $mail_body, $headers);