Cannot modify header information

Jeg får denne fejl:

Warning: Cannot modify header information - headers already sent by (output started at d:\web\TEST\YmAdmin\Send_mail_admin.php:163) in d:\web\TEST\YmAdmin\Send_mail_admin.php on line 181

Og jeg har prøvet at slette alle mellemrum men uden held: du kan se koden her da det er det sidste jeg mangler:

<?php
if (!empty($_GET)) {
extract($_GET);
} else if (!empty($HTTP_GET_VARS)) {
extract($HTTP_GET_VARS);
}
if (!empty($_POST)) {
extract($_POST);
} else if (!empty($HTTP_POST_VARS)) {
extract($HTTP_POST_VARS);
}
if (!isset($sub)){
include_once("head.php"); ?>

<table cellpadding="0" cellspacing="0" width="100%" class="bottomborder_top">
    <tr>
        <td><span class="TopText">Newsletter administration</span></td>
        <td align="right"><center><a href="<?php echo $_SERVER['PHP_SELF']; ?>">Departures admin</a> -
        <SCRIPT TYPE="text/javascript">
        <!--
        var bl = new backlink();
        bl.write();
        //-->
        </SCRIPT>
        </center></td>
    </tr>
</table>
<table cellpadding="2" cellspacing="2" border="0" width="100%">
    <tr>
        <td colspan="2">To send news letters you need to fill out the below form and press the send button. The newsletter will then be sent to all registered users at our foundation<br />
        To see the resent newsletter you should check the inbox for newsletters from us</td>
    </tr>
    <form action="<?php echo $_SERVER['PHP_SELF']; ?>?sub=send" method="post">
    <tr>
        <th>Subject:</th><td><input name="subject_text" value="" size="63" /></td>
    </tr>
    <tr>
        <th>Text:</th><td><textarea cols="48" rows="14" name="body_text"></textarea></td>
    </tr>
    <tr>
        <td colspan="2"><input type="submit" name="submit" value="Send newsletter" /></td>
    </tr>
    </form>
</table>


<?php include_once("footer.php");
}
if (isset ($_GET['sub']) && $sub == 'send'){
include_once ("auth.php");
if (!empty($_GET)) {
extract($_GET);
} else if (!empty($HTTP_GET_VARS)) {
extract($HTTP_GET_VARS);
}
if (!empty($_POST)) {
extract($_POST);
} else if (!empty($HTTP_POST_VARS)) {
extract($HTTP_POST_VARS);
}
    class smtp_client {
    var $connection;
    var $server;
    var $elog_fp;
    var $log_file='log/smtp.log';
    var $do_log=true;


    // default constructor
    function smtp_client($server='smtp.mail.dk') { //din udbyders smtp server
        if (!$server) $this->server="localhost";
        else $this->server=$server;
       
        $this->connection = fsockopen($this->server, 25);
        if ($this->connection <= 0) return 0;

        $this->elog(fgets($this->connection, 1024));
        $this->elog("HELO xyz\r\n", 1);
        fputs($this->connection,"HELO xyz\r\n");
        $this->elog(fgets($this->connection, 1024));
        }

    function email($from_mail, $to_mail, $to_name, $header, $subject, $body) {
        if ($this->connection <= 0) return 0;

        $this->elog("MAIL FROM:$from_mail", 1);
        fputs($this->connection,"MAIL FROM:$from_mail\r\n");
        $this->elog(fgets($this->connection, 1024));

        $this->elog("RCPT TO:$to_mail", 1);
        fputs($this->connection, "RCPT TO:$to_mail\r\n");
        $this->elog(fgets($this->connection, 1024));

        $this->elog("DATA", 1);
        fputs($this->connection, "DATA\r\n");
        $this->elog(fgets($this->connection, 1024));

        $this->elog("Subject: $subject", 1);
        $this->elog("To: $to_name", 1);
        fputs($this->connection,"Subject: $subject\r\n");
        fputs($this->connection,"To: $to_name\r\n");

        if ($header) {
            $this->elog($header, 1);
            fputs($this->connection, "$header\r\n");
            }

        $this->elog("", 1);
        $this->elog($body, 1);
        $this->elog(".", 1);
        fputs($this->connection,"\r\n");
        fputs($this->connection,"$body \r\n");
        fputs($this->connection,".\r\n");
        $this->elog(fgets($this->connection, 1024));

        return 1;
        }


    function send() {
        if ($this->connection) {
            fputs($this->connection, "QUIT\r\n");
            fclose($this->connection);
            $this->connection=0;
            }
        }

    function close() { $this->send(); }


    function elog($text, $mode=0) {
        if (!$this->do_log) return;

        // open file
        if (!$this->elog_fp) {
            if (!($this->elog_fp=fopen($this->log_file, 'a'))) return;
            fwrite($this->elog_fp, "\n-------------------------------------------\n");
            fwrite($this->elog_fp, " Sent " . date("Y-m-d H:i:s") . "\n");
            fwrite($this->elog_fp, "-------------------------------------------\n");
            }

        // write to log
        if (!$mode) fwrite($this->elog_fp, "    $text\n");
        else fwrite($this->elog_fp, "$text\n");
        }
    }


include_once ("../Forum/cfig.php");

$res = mysql_query("SELECT Email, Realname FROM users WHERE NewsLetter ='1'") or die (mysql_error());

$from = "support@mail.com"; //din egen mail :-)
$header = "Content-type: text/plain; charset=ISO-8859-1";
$subject = $_REQUEST['subject_text'];
$body = $_REQUEST['body_text'];

$smtp = new smtp_client;
$smtp -> smtp_client();

while (list($Email, $Realname) = mysql_fetch_row($res)) {
  $smtp->email("$from", "$Email", "$Realname", "$header", "$subject", "$body");
  echo "Mail sent to $Email<br />";
  }
$smtp->send();
mysql_close($db);

?>
<!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>
    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
</head>
<body leftmargin="0" topmargin="0">
Wait to be transfered back to the site.
</body>
</html>
<?php header("location: http://www.mysite.com/index.php");
        exit;
       
} ?>