PHP Ajax邮件始终失败

Question

我已经创建了一个脚本来发送带有ajax请求的电子邮件。发送邮件时，ajax会被执行，但 php邮件功能总是返回false 。所以AJAX if（data ==＆＃34; fail＆＃34;）一直在执行。任何人都知道为什么会这样？

php脚本：

if ($_SERVER["REQUEST_METHOD"] == "POST") {
$name       = strip_tags($_POST['naam']); 
$from       = filter_var(trim($_POST["email"]), FILTER_SANITIZE_EMAIL); 
$subject    = strip_tags($_POST['onderwerp']);
$message    = strip_tags($_POST['bericht']); 
$to         = 'someMail@gmail.com';

$headers   = array();
$headers[] = "MIME-Version: 1.0";
$headers[] = "Content-type: text/plain; charset=iso-8859-1";
$headers[] = "From: {$name} <{$from}>";
$headers[] = "Reply-To: <{$from}>";
$headers[] = "Subject: {$subject}";
$headers[] = "X-Mailer: PHP/".phpversion();

if (mail($to, $subject, $message, $headers)){
    echo 'success';
}else{
    echo 'fail';
}
}

和AJAX：

$(document).ready(function () {
    $('#contactKnop').on('click', function (event) {
        event.preventDefault();
        var naam = $('#naam').val();
        var email = $('#email').val();
        var bericht = $('#bericht').val();
        var onderwerp = $('#onderwerp').val();

        $.ajax({
            type: 'POST',
            url: 'mail.php',
            data: {
                naam: naam,
                email: email,
                onderwerp: onderwerp,
                bericht: bericht

            },
            //datatype: 'json',
            beforeSend: function () {
                $("div#divLoading").addClass('show');
            },
            complete: function () {
                $("div#divLoading").removeClass('show');
            },
            success: function (data) {
                if (data == "success") {
                    $('.emailformulier').slideUp(500);
                    $('#emailResultMessage').addClass('alert alert-success')
                    $('#emailResultMessage').text('We hebben uw bericht goed ontvangen.');
                    $('#emailResultMessage').show();
                    setTimeout(function () {
                        $("#emailResultMessage").slideUp(500)
                    }, 1000);
                    setTimeout(function () {
                        $("#emailResultMessage").text('')
                    }, 1500);
                }
                if (data == "fail") {
                    $('#emailResultMessage').addClass('alert alert-danger')
                    $('#emailResultMessage').text('Fout bij het versturen van uw bericht, probeer later opnieuw.');
                    $('#emailResultMessage').show();
                }
            },
            error: function () {
                alert('fout bij het versturen van de email');
            }
        });

    });
});