PHP的电子邮件形式不起作用。 HTML有效，但未发送电子邮件。用户输入的验证也不起作用

Question

所以，请有人帮我提供代码...我的电子邮件只是没有发送到我的电子邮件地址...非常感谢！单击按钮后，我认为我的html表单可以使用，但无法处理电子邮件发送。...对用户输入的验证（即，如果用户输入的电子邮件地址不带“ @”，则将无法验证。）有人可以吗？帮帮我.....谢谢

<?php
    include("head_nav.php");

    $name = "";
    $email = "";
    $telephone = "";
    $subject = "";
    $comments = "";

    $error_message = "";
    $email_message = "";
    $email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/';
    $string_exp = "/^[A-Za-z .'-]+$/";
    $email_owner = "(email)";

if(isset($_POST["submit"])) {

        function test_input($data) {
            $data = trim($data);
            $data = stripslashes($data);
            $data = htmlspecialchars($data);
            return $data;
        }

    // get input from form and sanitise it
    $name = test_input($_POST["name"]);
    $email = test_input($_POST["email"]);
    $telephone = test_input($_POST['telephone']);
    $subject = test_input($_POST['subject']);
    $comments = test_input($_POST["comments"]);

    function died($error) {
        // your error code can go here
        echo "We are very sorry, but there were error(s) found with the form you submitted. ";
        echo "These errors appear below.<br /><br />";
        echo $error."<br /><br />";
        echo "Please go back and fix these errors.<br /><br />";
        die();
    }

    // validation expected data exists
    if(!isset($_POST['name']) ||
        !isset($_POST['email']) ||
        !isset($_POST['telephone']) ||
        !isset($_POST['subject']) ||
        !isset($_POST['comments'])) {
        died('We are sorry, but there appears to be a problem with the form you submitted.');       

    }

    if(!preg_match($email_exp,$email)) {
        $error_message .= 'The Email Address you entered does not appear to be valid.<br />';
    }

    if(!preg_match($string_exp,$name)) {
        $error_message .= 'The name you entered does not appear to be valid.<br />';
    }

    if(strlen($subject) < 2) {
        $error_message .= 'The subject you entered do not appear to be valid.<br />';
    }

    if(strlen($comments) < 2) {
        $error_message .= 'The message you entered do not appear to be valid.<br />';
    }

    if(strlen($error_message) > 0) {
        died($error_message);
    }     

    $email_message .= "Name: ".clean_string($name)."\n";
    $email_message .= "Email: ".clean_string($email)."\n";
    $email_message .= "Subject: ".clean_string($subject)."\n";
    $email_message .= "Telephone: ".clean_string($telephone)."\n";
    $email_message .= "Comments: ".clean_string($comments)."\n";

    // create email headers
    $headers = 'MIME-VERSION: 1.0' . "\r\n";
    $headers .='content-type: text/html; charset=iso-8859-1' . "\r\n";
    $headers .= "From: $email";
    mail($email_owner, $subject, $email_message, $headers);  

    // create email headers
    // $headers = 'From: '.$email_from."\r\n".
    // 'Reply-To: '.$email_from."\r\n" .
    // 'X-Mailer: PHP/' . phpversion();
    // @mail($email, $subject, $email_message, $headers);  
}

?>

    <div class="content-container">
        <div style="padding:5vw;">
            <h2><b>Thank you for contacting us.</b></h2>
            <p> We will be in touch with you very soon. </p>
        </div>

<?php
    include("footer.php");
?>