public function send()
    {
        $subject = 'EVENT';
        if ($this->method == 'CANCEL') {

            $subject = 'CANCELED ' . $subject;
            if (empty($this->uid)) {
                throw(new \Exception('Must set uid to cancel an event.'));
            }
        }

        if (!empty($this->summary)) {
            $subject .= ': ' . substr($this->summary, 0, 20) . '...';
        }

        $to = '"' . $this->organizer->dname . '" <' . $this->organizer->email . '>';

        $mail = new \sb\Email($to, $subject, $this->summary, $to);
        $attendee_emails = Array();
        foreach ($this->attendees as $attendee) {
            $attendee_emails[] = '"' . $attendee->dname . '" <' . $attendee->email . '>';
        }

        $mail->cc = $attendee_emails;
        $mail->addIcalendarEvent($this);
        return $mail->send();
    }