<tr class="summary-details-1 summary-details summary-details-first">

<sales_email_order_items>
    <reference name="order_totals">
        <reference name="tax">
            <action method="setTemplate"><template>tax/order/tax-email.phtml</template></action>
        </reference>
    </reference>
</sales_email_order_items>

...
global $taxIter; $taxIter++;
...

...
$taxIter=0; $taxIter++;
...

public function send($email, $name = null, array $variables = array())
{
    if (!$this->isValidForSend()) {
        Mage::logException(new Exception('This letter cannot be sent.')); // translation is intentionally omitted
        return false;
    }

    $emails = array_values((array)$email);
    $names = is_array($name) ? $name : (array)$name;
    $names = array_values($names);
    foreach ($emails as $key => $email) {
        if (!isset($names[$key])) {
            $names[$key] = substr($email, 0, strpos($email, '@'));
        }
    }

    $variables['email'] = reset($emails);
    $variables['name'] = reset($names);

    $this->setUseAbsoluteLinks(true);
    $text = $this->getProcessedTemplate($variables, true);
    $subject = $this->getProcessedTemplateSubject($variables);

    $setReturnPath = Mage::getStoreConfig(self::XML_PATH_SENDING_SET_RETURN_PATH);
    switch ($setReturnPath) {
        case 1:
            $returnPathEmail = $this->getSenderEmail();
            break;
        case 2:
            $returnPathEmail = Mage::getStoreConfig(self::XML_PATH_SENDING_RETURN_PATH_EMAIL);
            break;
        default:
            $returnPathEmail = null;
            break;
    }

    if ($this->hasQueue() && $this->getQueue() instanceof Mage_Core_Model_Email_Queue) {
        /** @var $emailQueue Mage_Core_Model_Email_Queue */
        $emailQueue = $this->getQueue();
        $emailQueue->setMessageBody($text);
        $emailQueue->setMessageParameters(array(
                'subject'           => $subject,
                'return_path_email' => $returnPathEmail,
                'is_plain'          => $this->isPlain(),
                'from_email'        => $this->getSenderEmail(),
                'from_name'         => $this->getSenderName(),
                'reply_to'          => $this->getMail()->getReplyTo(),
                'return_to'         => $this->getMail()->getReturnPath(),
            ))
            ->addRecipients($emails, $names, Mage_Core_Model_Email_Queue::EMAIL_TYPE_TO)
            ->addRecipients($this->_bccEmails, array(), Mage_Core_Model_Email_Queue::EMAIL_TYPE_BCC);
        $emailQueue->addMessageToQueue();

        return true;
    }

    ...
}

->addRecipients($emails, $names, Mage_Core_Model_Email_Queue::EMAIL_TYPE_TO)

$emailQueue->addMessageToQueue();

public function wasEmailQueued(Mage_Core_Model_Email_Queue $queue)
{
    $readAdapter = $this->_getReadAdapter();
    $select = $readAdapter->select()
        ->from(
            array('recips' => $this->getTable('core/email_recipients')),
            array('recipient_email', 'recipient_name', 'email_type')
        )
        ->join(array('queue' => $this->getMainTable()), 'queue.message_id = recips.message_id', array())
        ->where('queue.entity_id =? ', $queue->getEntityId())
        ->where('queue.entity_type =? ', $queue->getEntityType())
        ->where('queue.event_type =? ', $queue->getEventType())
        ->where('queue.message_body_hash =? ', md5($queue->getMessageBody()));

    $existingRecipients = $readAdapter->fetchAll($select);
    if ($existingRecipients) {
        ...
           $queue->clearRecipients();
            foreach ($diff as $recipient) {
                list($email, $name, $type) = $recipient;
                $queue->addRecipients($email, $name, $type);
            }
        ...
    }

    return false;
}