public function addExportToBulkAction($observer)
    {
        $block = $observer->getBlock();
        if (
            $block instanceof Mage_Adminhtml_Block_Sales_Order_Grid &&
            Mage::helper('australia/clickandsend')->isClickAndSendEnabled()
        ) {
            $block->getMassactionBlock()->addItem('clickandsendexport', array(
                'label' => $block->__('Export to CSV (Click & Send)'),
                'url'   => $block->getUrl('*/australia_clickandsend/export')
            ));
        }
    }