$to_name = $to[$recipient]["name"];
    $email_message->SetEncodedEmailHeader("To", $to_address, $to_name);
    /* Do we really need to personalize the message body?
     * If not, let the class reuse the message body defined for the first recipient above.
     */
    if (!$email_message->cache_body) {
        /*
         *  Create a personalized body parts, either HTML and text
         *  alternative parts.
         */
        $first_name = strtok($to_name, " ");
        $balance = number_format($to[$recipient]["balance"], 2);
        $html_smarty->assign("firstname", HtmlEntities($first_name));
        $html_smarty->assign("balance", HtmlEntities($balance));
        $html_smarty->assign("email", HtmlEntities($to_address));
        $email_message->CreateQuotedPrintableHtmlPart($html_smarty->fetch("mailing.html.tpl"), "", $recipient_html_part);
        /* Make the personalized replace the initially empty HTML part */
        $email_message->ReplacePart($html_part, $recipient_html_part);
        $text_smarty->assign("firstname", $first_name);
        $text_smarty->assign("balance", $balance);
        $text_smarty->assign("email", $to_address);
        $email_message->CreateQuotedPrintableTextPart($email_message->WrapText($text_smarty->fetch("mailing.txt.tpl")), "", $recipient_text_part);
        /* Make the personalized replace the initially empty text part */
        $email_message->ReplacePart($text_part, $recipient_text_part);
    }
    /* Send the message checking for eventually acumulated errors */
    $error = $email_message->Send();
    if (strlen($error)) {
        break;
    }
}