how to get the delivered report for bounced message in GMail Inbox

Question

I am using Php mail Function/ SMTP To deliver my mail to my user for this I am using the below mentioned code . Mails are delivered properly .My problem is if I give any wrong e-mail ID in the "TO" address or I send mail to any wrong mail address, i did not get bounced messages delivered report in the Return-Path:Mail Id Inbox Instead it is delevered to the Return-path mail id spam folder.How to i get the bounced messages in the inbox, whats wrong with my code unless I should add any extra code. please guide me.

  $headers  = "MIME-Version: 1.0 \r\n";
                  $headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
                  $headers .= "from: <$almemailid>\r\n";
                  $headers .= "Return-Path: <$returnaddress>\r\n"; 
                  $headers .= "CC: <$sentcc>\r\n";
                  $headers .= "BCC: <$sentbcc>\r\n"; 
                  $headers .= "X-Mailer: PHP 4.x". phpversion();
        mail($snteadd[$m],$subjt,$message,$headers)

Thanks In advance