PHP标签在我的mailscript中不起作用

I want to send an email via PHP in HTML format the code shown below gives me the next problem: The mailscript is actually working but when the mail arrives and I open it the mail is displayed in html code. I actually want to make the HTML code work in the mail.

   <?php

    $headers = "From: " . strip_tags($_POST['emailadres']) . "
";
    $headers .= "Reply-To: ". strip_tags($to) . "
";
    $headers .= "CC: ".$to."
";
    $headers .= "MIME-Version: 1.0
";
    $headers .= "Content-Type: text/html; charset=ISO-8859-1
";

    $message = '<html><body>';
    $message .= '<img src="//css-tricks.com/examples/WebsiteChangeRequestForm/images/wcrf-header.png" alt="Website Change Request" />';
    $message .= '<table rules="all" style="border-color: #666;" cellpadding="10">';
    $message .= "<tr style='background: #eee;'><td><strong>Name:</strong> </td><td>" . strip_tags($_POST['voornaam']) . "</td></tr>";
    $message .= "<tr>
    <td>
    Vraagsteller
    </td>
    <td>
    ".$_POST['voornaam']."
    </td>
    </tr>";
    $message .= "<tr>
    <td>
    From
    </td>
    <td>
    ".$from."
    </td>
    </tr>";
    $message .= "<tr>
    <td>
    Titel
    </td>
    <td>
    ".$subject."
    </td>
    </tr>";
    $message .= "<tr>
    <td>
    Activatie link
    </td>
    <td>

    Link
    </a>
    </td>
    </tr>";
    $message .= "<tr>
    <td>
    Privacy
    </td>
    <td>
    ".checkPrive()."
    </td>
    </tr>";

    ?>

Try this

$to="abc@domain.com";

// Your subject
$subject="$sub";

// From
$from = "xyz@domain.com";

$headers = "MIME-Version: 1.0
";
$headers .= "Content-type: text/html; charset=iso-8859-1
";
$headers .= "From: <".$from.">
";
$headers .= "CC: cc@domain.com
"; 
$headers .= "X-Priority: 1
";

// Your message
$message= $text;
$send=mail($to,$subject,$message,$headers);