PHP: accept form and send as mail

sendmsg.php

<?php

$str = '';
foreach($_POST as $k => $v) {
    if(is_array($v)) {
        $v = implode(', ', $v);
    }
    $str .= "$k: $v\n";
}

$rnd = md5(time() + 'haha');

$headers = <<<EENNDD
MIME-Version: 1.0
Content-type: multipart/mixed; boundary="$rnd";
EENNDD;

$message = <<<EENNDD
--$rnd
Content-Type: text/plain; charset=utf-8

$str

EENNDD;

foreach($_FILES as $k => $f) {
    if($f['error']) continue;
    $fn = $f['name'];
    $type = $f['type'];
    $content = chunk_split(base64_encode(file_get_contents($f['tmp_name'])));
    $message .= <<<EENNDD
--$rnd
Content-Type: $type; name="$fn"
Content-Transfer-Encoding: base64
Content-Disposition: attachment

$content
EENNDD;
}

$message .= "--$rnd--";

if(isset($_POST['姓名'])) {
    $tail = '：' . $_POST['姓名'];
} else {
    $tail = '';
}

mail('feisuzhu@163.com', '客户信息' . $tail, $message, $headers);

?>

<script type="text/javascript">
alert("您的信息已经收到！我们会尽快联系您！");
window.location.href = 'index.html';
</script>