如何用AJAX实现reCAPTCHA在php中发送邮件？

<script src="https://www.google.com/recaptcha/api.js" async defer></script>
<form id="myForm">
  <!-- 其他表单字段 -->
  <div class="g-recaptcha" data-sitekey="YOUR_SITE_KEY"></div>
  <button type="submit">提交</button>
</form>

<?php
$recaptchaResponse = $_POST['g-recaptcha-response'];
$secretKey = 'YOUR_SECRET_KEY';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://www.google.com/recaptcha/api/siteverify');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
  'secret' => $secretKey,
  'response' => $recaptchaResponse
]));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);
$result = json_decode($response, true);

if ($result['success']) {
  // reCAPTCHA验证通过，继续发送邮件
  // 邮件发送逻辑
} else {
  // reCAPTCHA验证失败，给出错误提示
  echo 'reCAPTCHA验证失败';
}

curl_close($ch);
?>

<?php
$to = 'recipient@example.com';
$subject = '邮件主题';
$message = '邮件内容';
$headers = 'From: sender@example.com' . "\r\n" .
  'Reply-To: sender@example.com' . "\r\n" .
  'X-Mailer: PHP/' . phpversion();

if (mail($to, $subject, $message, $headers)) {
  echo '邮件发送成功';
} else {
  echo '邮件发送失败';
}
?>