What variables are available in notifications?

I'd like to customize the notification we receive when orders are placed.

How can I reference the email to use it in addition to SHIPPINGINFO

I see in helpers.php

$search_replace = array(
			'CUSTOMERNAME' => $customer_name,
			'ORDERID'      => $order->get_id(),
			'ORDERINFOSKU' => $order_info,
			'ORDERINFO'    => $order_info,
			'SHIPPINGINFO' => $shipping_billing_info,
			'PAYMENTINFO'  => $payment_info,
			'TOTAL'        => $order_total,
			'TRACKINGURL'  => $tracking_url,
			'ORDERNOTES'   => $order_notes,

I need CUSTOMEREMAIL