mail() geht nicht mehr nach Wechsel zu netcup

Ich habe nach dem Wechsel von Manitu zu netcup Webhosting 2000 ein Problem mit folgendem Script, das eine Bestellung als Mail an mich senden sollte (im Code unten anonymous@gmx.de): Der mail-Befehl funktioniert nicht, er gibt false zurück. Idee?

---

    [...]

    $body = base64_encode(
           
        "TOTAL="       . $total     . "\r\n" .
        "SURCHARGE="   . $surcharge . "\r\n" .
        "PP="          . $pp        . "\r\n" .
        "PRICE="       . $price     . "\r\n" .
        "ADDRESS:\r\n" . $address   . "\r\n"   
    );
    
    $boundary = "UHzpMtjpjtMvdtEJVP4nfCjHyWW6WJgs";
    
    $header =
    
        "From: mail@meine-netcup-domain.com\r\n" .
        "MIME-Version: 1.0\r\n" .
        "Content-Type: multipart/alternative;boundary=\"" . $boundary . "\"\r\n" . "--" . $boundary . "\r\n" .
        "Content-Type: text/plain; charset=UTF-8\r\n".
        "Content-Transfer-Encoding: base64\r\n";
    
    if (mail("anonymous@gmx.de)", "ORDER", $body, $header))
    { 
        $template = file_get_contents("report_template.html");
     
        if ($template)
        {   
            if ($pp < 0)
                $price_fmt = sprintf("%2d.%02d", -floor(abs($price) / 100), abs($price) % 100) . "&euro;";
            else
                $price_fmt = sprintf("%2d.%02d",  floor(abs($price) / 100), abs($price) % 100) . "&euro;";
    
            $template = str_replace("@PR_FORMATTED", $price_fmt, $template);
    
            // deliver page
        
            echo $template;
        }
        else
        {
            header("Location: http://www.meinedomain.com/division/circuits/onlineshop/php-error.html");
        }
    }
    else
    {
        echo "<html>";
        echo "<head>";
        echo "<title>Error</title>";
        echo "</head>";
        echo "<body>";
        echo "<p><strong>Error 404 - Mail error (your order was NOT received!)</strong></p>";
        echo "<p>Possible reasons:";
        echo "<ul>";
        echo "  <li>Server configuration error.</li>";
        echo "</ul>";
        echo "</body>";
        echo "</html>";
    }

    [...]

<?php

$email = $_GET['EMAIL'];

// validate e-mail

if ((strlen($email) < 64) && filter_var($email, FILTER_VALIDATE_EMAIL))
{
    $body = "\nEMAIL=" . $email;
    
    if (mail("anonymous@gmx.de", "REMINDER", $body, "From: Shop <mail@meine-netcup-domain.com>"))
    { 
        $template = file_get_contents("remind_template.html");
     
        if ($template)
        {   
            $find = array("EMAIL");
            $rplc = array( $email);
            
            $template = str_replace($find, $rplc, $template);

            // deliver page

            echo $template;
        }
        else
        {
            header("Location: http://www.meine-netcup-domain.com/onlineshop/php-error.html");
        }
    }
    else
    {
        echo "<html>";
        echo "<head>";
        echo "<title>Error</title>";
        echo "</head>";
        echo "<body>";
        echo "<p><strong>Error 404 - Mail error (Your request was NOT received!)</strong></p>";
        echo "<p>Possible reasons:";
        echo "<ul>";
        echo "  <li>Server configuration error.</li>";
        echo "</ul>";
        echo "</body>";
        echo "</html>";
    }
}
else
{
    header("Location: http://www.meine-netcup-domain.com/onlineshop/schedule.html");
}
?>