outlook - při přeposlání ztráta pův. odesílatele

function send_email($from, $to, $subject, $html_part, $text_part = '', array $attchFullPath = array(), $pars = array('replyTo' => '', 'copyTo' => '', 'bcc' => '')){
    $out = '';

    require_once(LIBS_DIR.'mailer/class.phpmailer.php');
    $mail = new PHPMailer();

    $mail->SetFrom($from);
    $mail->Subject = $subject;

    // V altbody zachovam odradkovani
    $tags = array('</p>','<br />','<br>','<hr />','<hr>','</h1>','</h2>','</h3>','</h4>','</h5>','</h6>');
    $alt = str_replace($tags,"\n",$html_part);
    $mail->AltBody = strip_tags($alt);

    $mail->AddAddress($to);//, "$Jmeno $Prijmeni");

    $mail->CharSet = "windows-1250";

    $mail->MsgHTML($html_part);

    // prilohy
    if (empty($attchFullPath) == false) {
        foreach ($attchFullPath as $file){
            $mail->AddAttachment($file);
        }//endforeach
    }

    if(!$mail->Send()) {
        $error = 'Mailer error: '.$mail->ErrorInfo;
        $out =  $error;
    }

    return $out;
}