title: captcha code interfering with form handler
body: <p>I'm trying to add captcha to a contact form on one of my sites using reCaptcha.
  the captcha works fine.
  the contact form works fine without the captcha-
  but when i add the code to validate the captcha it causes a problem.</p>
  
  <p>it gives me the following error message: </p>
  
  <blockquote>
    <p>Warning: Cannot modify header information - headers already sent by
    (output started at
    /home/liveoutl/domains/mydomainsample.com/public_html/bids/verify.php:1)
    in
    /home/liveoutl/domains/mydomainsample.com/public_html/bids/verify.php
    on line 53</p>
  </blockquote>
  
  <p>it sounds to me like the header is being interfered with - but there is no header per se.
  I'm trying to make it load a 'thank you' page when the form is submitted.
  this has always worked with the contact form handler script but now the captcha validation script is causing issues.</p>
  
  <p>is there a better way to load the thank you page?</p>
  
  <p>the following should be noted:
   I'm not very familiar with PHP
  I'm using an iframe to embed "contact-form.php" into the actual site</p>
  
  <p>here is my full code in verify.php:</p>
  
  <pre><code>&lt;!-- begin code for including captcha validation--&gt;    
  &lt;?php
        require_once('recaptchalib.php');
        $privatekey = "private_key";
        $resp = recaptcha_check_answer ($privatekey,
                                      $_SERVER["REMOTE_ADDR"],
                                      $_POST["recaptcha_challenge_field"],
                                      $_POST["recaptcha_response_field"]);
  
        if (!$resp-&gt;is_valid) {
          // What happens when the CAPTCHA was entered incorrectly
          die ("The reCAPTCHA wasn't entered correctly. Go back and try it again." .
               "(reCAPTCHA said: " . $resp-&gt;error . ")");
        } else {
          // Your code here to handle a successful verification
        }
        ?&gt;
        &lt;!-- from here down handles the actual processing and sending of the form--&gt;
        &lt;?php 
      $errors = '';
      $myemail = 'name@domain.com';//&lt;-----Put Your email address here.
      if(empty($_POST['name'])  || 
         empty($_POST['email']) ||
         empty($_POST['phone']) ||
         empty($_POST['message']))
      {
          $errors .= "\n Error: all fields are required";
      }
  
      $name = $_POST['name']; 
      $email_address = $_POST['email']; 
      $phone_number = $_POST['phone'];
      $message = $_POST['message']; 
  
      if (!preg_match(
      "/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/i", 
      $email_address))
      {
          $errors .= "\n Error: Invalid email address";
      }
  
      if( empty($errors))
      {
          $to = $myemail; 
          $email_subject = "Contact form submission: $name";
          $email_body = "You have received a new message. ".
          " Here are the details:\n Name: $name \n Email: $email_address \n Phone: $phone_number \n Message \n $message"; 
  
          $headers = "From: $myemail\n"; 
          $headers .= "Reply-To: $email_address";
  
          mail($to,$email_subject,$email_body,$headers);
          //redirect to the 'thank you' page
          header('Location: contact-form-thank-you.html');
      } 
      ?&gt;
      &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"&gt; 
      &lt;html&gt;
      &lt;head&gt;
          &lt;title&gt;Contact form handler&lt;/title&gt;
      &lt;/head&gt;
  
      &lt;body&gt;
      &lt;!-- This page is displayed only if there is some error --&gt;
      &lt;?php
      echo nl2br($errors);
      ?&gt;
  
  
      &lt;/body&gt;
      &lt;/html&gt;
  </code></pre>