Simple PHP Contact Script

gistfile1.php

<?php
  if(isset($_POST['email'])) {
     
    // EDIT THE 2 LINES BELOW AS REQUIRED
    $email_to = "email@yourdomain.com";
    $email_subject = "Email Subject line";
     
     
    function died($error) {
        ?>
          <h2>Oops! Something's not right.</h2>
          <p><?php echo $error."<br /><br />"; ?></p>
        <?php
        die();
    }
     
    $name = $_POST['name']; 
    $email_from = $_POST['email'];
    $message = $_POST['message'];
     
    $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)) {
      $error_message .= 'The name you entered does not appear to be valid.<br />';
    }
    if(strlen($message) < 2) {
      $error_message .= 'The message you entered do not appear to be valid.<br />';
    }
    if(strlen($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);
    }
     
    $email_message .= "Name: ".clean_string($name)."\n";
    $email_message .= "Email: ".clean_string($email_from)."\n";
    $email_message .= "Message: ".clean_string($message)."\n";

    $headers = 'From: '.$email_from."\r\n".
    'Reply-To: '.$email_from."\r\n";
    mail($email_to, $email_subject, $email_message, $headers); 

    ?>
      <p>Thank you for contacting us. We will be in touch with you very soon.</p>
    <?php
  }
?>