PHP: HTML wysyła e-mail w formacie html

Śledzę samouczekhttp://css-tricks.com/sending-nice-html-email-with-php/ wysyłać pocztę w formacie html.

Mój ciąg wygląda jak

$message = '<html><body>';
$message .= '<img src="http://css-tricks.com/examples/WebsiteChangeRequestForm/images/wcrf-header.png" alt="Website Change Request" />';
$message .= '<table rules="all" style="border-color: #666;" cellpadding="10">';
$message .= "<tr style='background: #eee;'><td><strong>Dear:</strong> </td><td>" . strip_tags($part_name). "</td></tr>";
$message .= "<tr><td><strong>.$user_name.has fixed an appointment with you on  :</strong> </td><td>" . strip_tags($time). "</td></tr>";
$message .= "<tr><td><strong>In:</strong> </td><td>" .  strip_tags($meeting_name) . "</td></tr>";
$message .= "<tr><td><strong>Please click on:</strong> </td><td><a href=" . strip_tags($approve_url). "</a> To approve</td></tr>";
$message .= "</table>";
$message .= "</body></html>";

//   CHANGE THE BELOW VARIABLES TO YOUR NEEDS

$subject = 'Appointment Request ';

$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: text/html; charset=ISO-8859-1\r\n";

Ale otrzymana poczta nie jest sformatowana w HTML, ale wygląda jak

<html>
    <body>
        <img src="http://css-tricks.com/examples/WebsiteChangeRequestForm/images/wcrf-header.png" alt="Website Change Request" />
        <table rules="all" style="border-color: #666;" cellpadding="10">
            <tr style='background: #eee;'>
                <td>
                    <strong>Dear:</strong> 
                </td>
                <td>Depu</td>
            </tr>
            <tr>
                <td>
                    <strong>.pandit.has fixed an appointment with you on  :</strong> 
                </td>
                <td>
                </td>
            </tr>
            <tr>
                <td>
                    <strong>In:</strong>
                </td>
                <td>anyp</td>
            </tr>
            <tr>
                <td>
                    <strong>Please click on:</strong>
                </td>
                <td>
                    <a href=http://192.168.0.178/UI/user/approvemeeting.php?meetingid=REG_939300945&key=3107</a> To approve
                </td>
            </tr>
        </table>
    </body>
</html>

Proszę mi powiedzieć, co robię źle, dlaczego poczta nie jest w formacie HTML

questionAnswers(2)

yourAnswerToTheQuestion