如何在php中声明全局变量以接收自定义电子邮件？

我正在做我的投资组合，在它的末尾，有一个表格（姓名、电子邮件、消息）。此表单需要向我的个人gmail帐户发送电子邮件，但我在设置全局变量时遇到了困难

表单正在运行，这是html代码

            <form action="" method="POST" id="contact-form">
              <span class="contacts-text" id="first-contacts-text">To get in touch with me, please compile this form.</span>
              <span class="contacts-text">I will reply as soon as possible. Thank you!</span>
              <ul class="form-content">
                  <li class="form-input">
                      <label for="name" class="label">Full name</label>
                      <input class="input" id="name" type="text" name="name" required>
                  </li>
                  <li class="form-input">
                      <label for="email" class="label">E-mail</label>
                      <input class="input" id="mail" type="text" name="email" required>
                  </li>
                  <li class="form-input">
                      <label for="msg" class="label">Insert text</label>
                      <textarea class="input" id="comment" type="text" name="msg" cols="30" rows="10" style="resize: none;" required></textarea>
                  </li>
                  <li class="form-input" id="last-input">
                      <input class="input" id="form-button" type="submit" value="submit" name="submit" onclick="sendEmail()">
                  </li>
              </ul>
            </form>

这段代码运行良好，我正在接收电子邮件，但我需要这些变量的帮助。

---

提前谢谢。

我解决了。我使用这个脚本“$message=$\u POST['msg']]？”，清除了函数外部的变量（在php.index的顶部）；我错拼了输入lol的名称值，noob error。

  use PHPMailer\PHPMailer\PHPMailer;
  use PHPMailer\PHPMailer\SMTP;
  use PHPMailer\PHPMailer\Exception;

  require 'vendor/autoload.php';

  $mail = new PHPMailer(true);

  try {

    $mail->Host='smtp.gmail.com';
    $mail->SMTPDebug = 0;
    $mail->isSMTP();
    $mail->Port=587;
    $mail->SMTPAuth=true;
    $mail->SMTPSecure='tls';
    $mail->Username='myemail@gmail.com';
    $mail->Password='mypassword';

    $mail->setFrom('myotheremail@gmail.com'); //i know that i have to put here a variable for client email
    $mail->addAddress('myemail@gmail.com');

    $mail->isHTML(true);
    $mail->Subject = 'Portfolio response';
    $mail->Body = ''; // here probably another variable for the content
    $mail->send();
     echo '';
    } catch (Exception $e){
        echo 'Something went wrong!'. $mail->ErrorInfo;
    }