我創(chuàng)建了一個聯(lián)系頁面，但是當我通過向網(wǎng)站的電子郵件地址（gmail 地址）發(fā)送電子郵件來測試它時，它顯示一個白色頁面這是我的聯(lián)系表單的 php 代碼<?phpif (isset ($_POST['submit'])) {    $name = $_POST ['name'];    $mailFrom = $_POST ['email'];    $message = $_POST ['message'];$mailto = "lawsafrica@gmail.com";$headers = "From: ".$mailFrom;$txt = "You have received an e-mail from ".$name.".\n\n".$message;mail($mailTo, $txt, $headers);header ("Location: Contact.html?mailsend"); }這是我的 html 代碼 (contact.html) <section class="box1">    <h2>Contact us</h2>    <div class="lines"></div>   <form class="contact-form" action="contactform.php" method= "POST">         <input type= "text" class= "contact-form-text" placeholder="Your name" required>        <input type= "Email" class= "contact-form-text" placeholder="Your email"required>        <textarea class="contact-form-text" placeholder="Your message"required></textarea>        <input type="submit" class="contact-form-btn"value="Send">    </form></section><section class= "box2">    <h3>Didn't find what you are looking for?</h3>    <div class="lines"></div>    <form class="contact-form"  action="contactform.php" method= "POST" >             <input type= "text" name= "name" class= "contact-form-text" placeholder="Your name"required>        <input type= "Email" name= "email" class= "contact-form-text" placeholder="Your email"required>        <textarea class="contact-form-text" name= "message" placeholder="Type what are you looking for"required></textarea>        <input type="submit"  name= "submit" class="contact-form-btn"value="Send">    </form></section><section class= "box3">    <h4>Become a contributor</h4>    <div class="lines"></div>    <form class="contact-form" action="uploads.php" method= "POST" enctype= "multipart/form-data">         <input type= "file" class= "contact-form-text" >        <button type="submit" class="contact-form-btn" name= "submit">Upload</button>    </form></section>