Gensender formular

Hej

Jeg har et problem med min kontaktformular. Når jeg har sendt den og trykker opdater i browseren bliver den samme email sendt igen og man kan på den måde spamme min email.

Kan man gøre noget ved dette udover tilføje AJAX?

contact.php:

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" id="contact_form" method="post">
                         
                    <?php echo $response; ?>
                         
                    <div id="form_fields">

                        <input type="hidden" name="string" id="string" value="<?php echo $new_string; ?>" />
       
                        <p><label for="name">Name:</label>
                        <input class="text_field required" minlength="2" type="text" name="name" id="name" /></p>
                                   
                        <p><label for="email">Email:</label>
                        <input class="text_field required" type="text" name="email" id="email" /></p>
                                   
                        <p><label for="subject">Subject:</label>
                        <input class="text_field required" type="text" name="subject" id="subject" /></p>
                           
                        <p><label for="message">Message:</label>
                        <textarea class="text_area required" rows="10" name="message" id="message" ></textarea></p>
                                   
                        <p><label for="verification">Verification</label>
                        <?php
                                echo "<img class=\"verification_image\" src=\"verification.png\" alt=\"Verification\" />";
                                echo "<input class=\"text_field verification_input required\" name=\"verification\" id=\"verification\" type=\"text\" value=\"\" /></p>";
                        ?>

                        <span class="button_margin"><input type="submit" value="Submit" name="submit" id="submit" class="button" /></span>
                               
                  </div> <!-- end form_fields -->

                </form>

og sendEmail.php:

<?php

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

    $string            = $_POST['string'];
    $name             = trim($_POST['name']);
    $email             = $_POST['email'];
    $subject         = $_POST['subject'];
    $message         = $_POST['message'];
    $verification     = $_POST['verification'];
   
    $site_owners_email = 'steffan@lildholdt.dk'; // Replace this with your own email address
    $site_owners_name = 'Test Name'; // Replace with your name
   
    // Check for error in the name field
    if (empty($name)) {
        $error['name'] = "Please enter your full name";   
    }
   
    // Check for error in the email field
    if (!preg_match('/^[a-z0-9&\'\.\-_\+]+@[a-z0-9\-]+\.([a-z0-9\-]+\.)*+[a-z]{2}/is', $email)) {
        $error['email'] = "Please enter a valid email address";   
    }
   
    // Check for error in the subject field
    if (empty($subject)) {
        $error['subject'] = "Please enter a subject";   
    }
   
    // Check for error in the message field
    if (empty($message)) {
        $error['message'] = "Please enter a message.";
    }
   
    // Check for error in the verification field
    if ($verification != $string) {
        $error['verification'] = "The verification code was wrong.";
    }
   
    // If no error occured send the email
    if (!$error) {
       
        require_once('phpMailer/class.phpmailer.php');
        $mail = new PHPMailer();
       
        $mail->From = $email;
        $mail->FromName = $name;
        $mail->IsHTML(true);
        $mail->Subject = $subject;
        $mail->AddAddress($site_owners_email, $site_owners_name);
       
        $mail->Body = $message;

        $mail->Send();
       
        $response = "<ul class=\"email_succes\"> <li> Congratulations, " . $name . ". We've received your email. We'll be in touch as soon as we possibly can. </li></ul>";
       
    } // end if no error
    else {
       
        $response = "<ul class=\"email_error\">";
        $response .= (isset($error['name'])) ? "<li>" . $error['name'] . "</li> \n" : null;
        $response .= (isset($error['email'])) ? "<li>" . $error['email'] . "</li> \n" : null;
        $response .= (isset($error['subject'])) ? "<li>" . $error['subject'] . "</li> \n" : null;
        $response .= (isset($error['message'])) ? "<li>" . $error['message'] . "</li>" : null;
        $response .= (isset($error['verification'])) ? "<li>" . $error['verification'] . "</li>" : null;
        $response .= "</ul>";
       
    } // end if there was an error sending

}
?>