PHP shows up blank inf IE & Firefox but not Safari
===

I am new to php & have a simple "tell a friend" code. A popup is suppose to come up & show that the message has been sent to the friend. This works great in Safari, however it shows up blank in IE & Firefox. 

Below is the code:

    <?php
    if(isset($_POST['email'])) {
     
    $email_to = "speedyblindsdfw@gmail.com";
    $email_subject = "Check this site out!"; 
     
    function died($error) {
        //error code 
        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();
      }
     
      // validation expected data exists
      if(!isset($_POST['senders_email']) ||
        !isset($_POST['email'])) {
        died('We are sorry, but there appears to be a problem with the form you submitted.');       
      }

    $email_from = $_POST['senders_email']; // required
    $email = $_POST['email']; // not 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 />';
    }

    if(strlen($error_message) > 0) {
    died($error_message);
    }
     
     function clean_string($string) {
      $bad = array("content-type","bcc:","to:","cc:","href");
      return str_replace($bad,"",$string);
    }
    $email_message .= "I was on this site today & thought you would be interested.";
    $email_message .= "\nwww.primaresidential.com\n\n";
    $email_message .= "Dear " .clean_string($email). ",";       
    $email_message .= "\nYour friend, " .clean_string($email_from). " had linked";
    $email_message .= "our site to your email, we hope you enjoy our site as much as they did!"; 
    $email_message .= "\n\nPrima Residential Services."; 
 
    //email headers
    $headers = 'From: '.$email_from."\r\n".
    'Reply-To: '.$email_from."\r\n" .
    'X-Mailer: PHP/' . phpversion();	
     @mail($email_to, $email_subject, $email_message, $headers);
     @mail($email, $email_subject, $email_message, $headers);  
     ?>
 
      <!----HTML CODE------>

      <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
      <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
      <head>
        <title>PrimaResidential Serivces- Emailer</title> 
           <style type="text/css" media="all">@import "css/style.css";</style>  
           <style type="text/css" media="all">@import "css/style.css";</style>
   
        
          </head>
        <br/><br/><br/><br/><br/>
            <div class="boxbg all-round" id="page-container-Popup">
            <br/><br/><br/><br/><br/><center>
            <h2>Your email was successfully sent.</h2><br>
            <br><h3>Thank you for spreading the word.<br>
               <font size="1"> Be sure to check your email in the next 2-3 business days for a little surprise.</font></h3>
            <br/></center>
            
            </div>
            <a href="javascript:window.close()">Close Window</a>      
            
                        
         </body>
         </html>

         <?php
          }
         ?>



Please let me know if you see what I did wrong or what I need to add. Thanks :) 

    