Отправка запросов ajax

<?
if ($_SERVER['REQUEST_METHOD'] == 'POST'):

$result = array();  

function fetchUrl($url, $postFields = array())
{
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_HEADER, false);
    curl_setopt($ch, CURLOPT_POST, true);
    $headers = [
        'Content-Type: application/json; charset=utf-8'
    ];
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    if(!empty($postFields)) {
        curl_setopt($ch, CURLOPT_POSTFIELDS, $postFields);
    }
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    $response = array();
    $response['html']     = curl_exec($ch);
    $response['err']      = curl_errno($ch);
    $response['errmsg']   = curl_error($ch);
    $response['header']   = curl_getinfo($ch);
    curl_close($ch);
    return $response;
}
$json = json_decode($_POST['json']);

$response = fetchUrl('http://rd.dev.rosdengi.com/api/leads?app_id=57a0a0869ab5746393c8c258&token=f7690ea0-82f3-11e6-8e33-b780694548e0&v=13', json_encode($json));

$result['result'] = $response;

$resp = json_decode($response['html']);

$error = '';

foreach ($resp as $keyses => $valueses) 
{
    if ($keyses == 'leadId') $error = 'N';
    break;
}

if ($error === 'N') 
{
    $headers = "MIME-Version: 1.0\r\n";
    $headers .= "Content-type: text/plain; charset=\"utf-8\"";

    $str = '';

    foreach ($json as $k => $v) 
    {
        if ($v == '' || $k == 'contacts') {
            continue;
        }
        $str .= $k . ': ' . $v . "\r\n";
    }
    foreach ($resp as $ke => $va)
    {
        $leadId = $va;
        break;
    }
    

    $message = "Данные пользователя: \r\n" . $str . "\r\n";
    $message .= 'leadId: ' . $leadId . "\r\n";
    
    /* и теперь отправим из */
    mail('[email protected]', 'Json ответ с сервера API', $message, $headers);
}
echo json_encode($result);
die();
endif;
?>