Contact form submitting regardless of Recaptcha
<p>Hi I'm trying to install Google Recaptcha onto my contact form. Recaptcha is displaying fine but at the moment the form will submit even if Captcha not attempted. </p>

<p>I've posted the code below, would appreciate any help :)</p>

<pre><code>&lt;?php

/* =====================================================
 * change this to the email you want the form to send to
 * ===================================================== */
$email_to = ";
$email_subject = "Contact Form submitted";

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

    function return_error($error)
    {
        echo $error;
        die();
    }

    // check for empty required fields
    if (!isset($_POST['name']) ||
        !isset($_POST['email']) ||
        !isset($_POST['message'])

)
    {
        return_error('Please fill in all required fields.');
    }

    // form field values
    $name = $_POST['name']; // required
    $email = $_POST['email']; // required
    $contact_number = $_POST['contact_number']; // not required
    $message = $_POST['message']; // required
    $enquiry = $_POST['enquiry'];


    // form validation
    $error_message = "";

    // name
    $name_exp = "/^[a-z0-9 .\-]+$/i";
    if (!preg_match($name_exp,$name))
    {
        $this_error = 'Please enter a valid name.';
        $error_message .= ($error_message == "") ? $this_error : "&lt;br/&gt;".$this_error;
    }        

    $email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/';
    if (!preg_match($email_exp,$email))
    {
        $this_error = 'Please enter a valid email address.';
        $error_message .= ($error_message == "") ? $this_error : "&lt;br/&gt;".$this_error;
    } 

    // if there are validation errors

    if(strlen($error_message) &gt; 0)
    {
        return_error($error_message);
    }

    // prepare email 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);
    }

    $email_message .= "Enquiry Type: ".clean_string($enquiry)."\n";
    $email_message .= "Name: ".clean_string($name)."\n";
    $email_message .= "Email: ".clean_string($email)."\n";
    $email_message .= "Contact number: ".clean_string($contact_number)."\n";
    $email_message .= "Message: ".clean_string($message)."\n";

    // create email headers
    $headers = 'From: '.$email."\r\n".
    'Reply-To: '.$email."\r\n" .
    'X-Mailer: PHP/' . phpversion();
    //var_dump($email_to); var_dump($email_subject); var_dump($email_message); var_dump($headers);  
    if (mail($email_to, $email_subject, $email_message, $headers))
    {
        echo 'Form submitted successfully.';
    }
    else 
    {
        echo 'An error occured. Please try again later.';
        die();        
    }
}
else
{
    echo 'Please fill in all required fields.';
    die();
}
?&gt;

&lt;?php   
    if(isset($_POST['g-recaptcha-response']) &amp;&amp; !empty($_POST['g-recaptcha-response'])){
        $privatekey = "";

        //get verified response data
        $param = "https://www.google.com/recaptcha/api/siteverify?secret=".$privatekey."&amp;response=".$_POST['g-recaptcha-response'];
        $verifyResponse = file_get_contents($param);
        $responseData = json_decode($verifyResponse);

        if($responseData-&gt;success){
            // success
            echo "success";

        }else{
            // failure
            echo "failure";
        }
    }else{
        // user didn't enter reCAPTCHA
        echo "The reCAPTCHA wasn't entered correctly. Go back and try it again.";
    }
?&gt;
</code></pre>