public function addIcalendarEvent(\sb\ICalendar\Event $event)
    {

        $a = new \sb\Email\Attachment();
        $a->mime_type = 'text/calendar;';
        $a->setEncoding('8bit');
        $a->name = 'event.ics';
        $a->contents = $event->__toString();

        $this->addAttachment($a);
    }