PHP脚本是正确的，但不发送

I am having difficulty with my php code. From my tired eyes, the code is correct, and I've had multiple others look at the code. No one can figure out why it's not working. It must be something quite simple, but I cannot get the contact form to send.

PHP script:

<?php


$from = 'email@example.com';
$sendTo = 'email@example.com';
$subject = 'New message from contact form';
$fields = array('name' => 'Name', 'surname' => 'Surname', 'phone' => 'Phone', 'email' => 'Email', 'message' => 'Message');
$htmlHeader = '';
$htmlFooter = '';
$okMessage = 'Contact form succesfully submitted. Thank you, We will get back to you soon!';

$htmlContent = '<h1>New message from contact form</h1>';



use Nette\Mail\Message,
    Nette\Mail\SendmailMailer;


require 'php/Nette/nette.phar';


$configurator = new Nette\Configurator;
$configurator->setTempDirectory(__DIR__ . '/php/temp');
$container = $configurator->createContainer();


$httpRequest = $container->getService('httpRequest');
$httpResponse = $container->getService('httpResponse');

$post = $httpRequest->getPost();

if ($httpRequest->isAjax()) {

    $htmlContent .= '<table>';
    foreach ($post as $key => $value) {

    if (isset($fields[$key])) {
        $htmlContent .= "<tr><th>$fields[$key]</th><td>$value</td></tr>";
    }
    }
    $htmlContent .= '</table>';


    $htmlBody = $htmlHeader . $htmlContent . $htmlFooter;


    $mail = new Message;
    $mail->setFrom($from)
        ->addTo($sendTo)
        ->setSubject($subject)
        ->setHtmlBody($htmlBody, FALSE);

    $mailer = new SendmailMailer;
    $mailer->send($mail);


    $responseArray = array('type' => 'success', 'message' => $okMessage);

    $httpResponse->setCode(200);
    $response = new \Nette\Application\Responses\JsonResponse($responseArray);
    $response->send($httpRequest, $httpResponse);
}

Contact Form HTML:

<div class="section contact soepa" id="contact" data-animate="bounceIn">
    <div class="container">
        <div class="col-md-12">


            <h2 class="title"><span style="color: #f46b01;">Connect With Us</span></h2>

            <div class="row">

                <div class="col-md-8 col-md-offset-2">
                    <form id="contact-form" method="post" action="contact.php">

                        <div class="messages">

                        </div>

                        <div class="controls">

                            <div class="row">
                                <div class="col-md-6">
                                    <input type="text" name="name" class="form-control" placeholder="Your firstname *" required="required">
                                </div>
                                <div class="col-md-6">
                                    <input type="text" name="surname" class="form-control" placeholder="Your lastname *" required="required">
                                </div>
                                <div class="col-md-6">
                                    <input type="text" name="email" class="form-control" placeholder="Your email *" required="required">
                                </div>
                                <div class="col-md-6">
                                    <input type="text" name="phone" class="form-control" placeholder="Your phone *" required="required">
                                </div>

                                <div class="col-md-12">
                                    <textarea name="message" class="form-control" placeholder="Message *" rows="4" required="required"></textarea>
                                </div>
                                <div class="col-md-12 text-center">
                                    <input type="submit" class="btn btn-primary btn-lg" value="Send message">
                                </div>
                            </div>
                        </div>

                    </form>
                </div>

            </div>

        </div>
    </div>
</div>