PHP电子邮件列表订阅服务器脚本

为什么这个脚本不能工作？我只想发一封电子邮件给hello@weblabcompany.com用订户的电子邮件，这样我以后可以跟进他们

<div class="col-2" id="sub-box">
                <h1 class="text-white margin-bottom"> Subscribe to Web Lab </h1>
                <h2 class="text-white margin-bottom"> Receive articles as they are published </h2>
                <form name="subscribe" action="/submail.php" method="post"> <input type="email" value="Email"> <input type="submit" value="Send" class="width-25"> </form>
            </div>

    <?php
if(isset($_POST['email'])) {

 // EDIT THE 2 LINES BELOW AS REQUIRED
$email_to = "hello@weblabcompany.com";
$email_subject = "New Sub";
function died($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();
}

!isset($_POST['email']) 
 {
died('We are sorry, but there appears to be a problem with the form you submitted.');       
}

$email = $_POST['email']; // required

//$error_message = "";
//$email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+'.[A-Za-z]{2,4}$/';
//if(!preg_match($email_exp,$email_from)) {
//$error_message .= 'The Email Address you entered does not appear to be valid.<br />';
//}
//$string_exp = "/^[A-Za-z .'-]+$/";
//if(!preg_match($string_exp,$name)) {
//$error_message .= 'The First Name you entered does not appear to be valid.<br />';
//}
//if(!preg_match($string_exp,$email)) {
//$error_message .= 'The Last Name you entered does not appear to be valid.<br />';
//}
//if(strlen($message) < 2) {
//$error_message .= 'The Comments you entered do not appear to be valid.<br />';
//}
//if(strlen($error_message) > 0) {
//died($error_message);
//}
$email_message = "Form details below.'n'n";    
function clean_string($string) {
$bad = array("content-type","bcc:","to:","cc:","href");
return str_replace($bad,"",$string);
}

$email_message .= "email: ".clean_string($email)."'n";

$headers = 'From: '.$email_from."'r'n".
'Reply-To: '.$email_from."'r'n" .
 'X-Mailer: PHP/' . phpversion();
@mail($email);  
?>
 <!-- include your own success html here -->
Thank you for contacting us. We will be in touch with you very soon. 
<?php
}
?>