<form id="ajax-contact" class="main-contact submit-fade ajax-form" action="register.php" method="POST">
      <ul class="small-block-grid-2 medium-block-grid-2 hide-form">
        <li>
          <label for="name">Name</label>
          <input type="text" class="form-control" name="name" placeholder="Name" required>
        </li>

        <li>
          <label for="email">Email</label>
          <input type="text" class="form-control" name="email" placeholder="Email">
        </li>
      </ul>
      <input type="submit" class="btn btn-success">
    </form>

var form = $('#ajax-contact');


   var formMessages = $('#form-messages');

  $(form).submit(function(e) {

   e.preventDefault();


  var formData = $(form).serialize();

// Submit the form using AJAX.
$.ajax({
    type: 'POST',
    url: $(form).attr('action'),
    data: formData
  })
  .done(function(response) {
    // Make sure that the formMessages div has the 'success' class.
    $(formMessages).removeClass('error');
    $(formMessages).addClass('success');

    // Set the message text.
    $(formMessages).text(response);

    // Clear the form.
    $('#name').val('');
    $('#email').val('');
    //$('#message').val('');
  })
  .fail(function(data) {
    // Make sure that the formMessages div has the 'error' class.
    $(formMessages).removeClass('success');
    $(formMessages).addClass('error');

    // Set the message text.
    if (data.responseText !== '') {
      $(formMessages).text(data.responseText);
    } else {
      $(formMessages).text('Oops! An error occured and your message could not be sent.');
    }
  });

 });

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Get the form fields and remove whitespace.
    $name = strip_tags(trim($_POST["name"]));
            $name = str_replace(array("r","n"),array(" "," "),$name);
    $email = filter_var(trim($_POST["email"]), FILTER_SANITIZE_EMAIL);
    $message = trim($_POST["message"]);

    // Check that data was sent to the mailer.
    if ( empty($name) OR empty($message) OR !filter_var($email, FILTER_VALIDATE_EMAIL)) {
        // Set a 400 (bad request) response code and exit.
        http_response_code(400);
        echo "Oops! There was a problem with your submission. Please complete the form and try again.";
        exit;
    }

    // Set the recipient email address.
    // FIXME: Update this to your desired email address.
    $recipient = "hello@example.com";

    // Set the email subject.
    $subject = "New contact from $name";

    // Build the email content.
    $email_content = "Name: $namen";
    $email_content .= "Email: $emailnn";
    $email_content .= "Message:n$messagen";

    // Build the email headers.
    $email_headers = "From: $name <$email>";

    // Send the email.
    if (mail($recipient, $subject, $email_content, $email_headers)) {
        // Set a 200 (okay) response code.
        http_response_code(200);
        echo "Thank You! Your message has been sent.";
    } else {
        // Set a 500 (internal server error) response code.
        http_response_code(500);
        echo "Oops! Something went wrong and we couldn't send your message.";
    }

} else {
    // Not a POST request, set a 403 (forbidden) response code.
    http_response_code(403);
    echo "There was a problem with your submission, please try again.";
}

  ?>