与联系表格一起发送时未收到电子邮件

当我在制作的网站上填写联系表格时，会发送电子邮件，但我的电脑收件箱中没有收到。代码如下：

HTML:

<div id="form">
    <form action="mailto:psteintj@xs4all.nl" id="contactForm" method="post">
        <span></span>
        <input type="text" name="name" class="name" placeholder="Enter your name" tabindex=1 />
        <span></span>
        <input type="text" name="email" class="email" placeholder="Enter your email" tabindex=2 />
        <span id="captcha"></span>
        <input type="text" name="captcha" class="captcha" maxlength="4" size="4" placeholder="Enter captcha code" tabindex=3 />
        <span></span>
        <textarea class="message" placeholder="Enter your message" tabindex=4></textarea>
        <input type="submit" name="submit" value="Send e-mail" class="submit" tabindex=5>
    </form>
</div>

JS:

if ((captchaVal == captchaCode) && (emailFilter.test(emailText)) && (nameFilter.test(nameText)) && (messageText > 50)) {
  $.post("mail.php", {
  name: $(".name").val(),
  email: $(".email").val(),
  message:$(".message").val()
  }); 
  $("#contactForm").css("display", "none");
  $("#form").append("<h2>Message sent!</h2>");
  return false;
}

和PHP:

<?php
$name = $POST['name'];
$email = $_POST['email'];
$message = $POST['message'];

有人能告诉我哪里出了问题吗？