class-email.php

<?php
/**
  * Class for sending tracking emails
  * For reference on WC_Emails class see https://docs.woocommerce.com/wc-apidocs/class-WC_Emails.html
  * @author: Michael Schönrock (ms@halloecho.de)
  */
  
class Tracking_Email extends WC_Emails {

	public function generate_message($tracking_number, $customer_name) {
		
		$return = 'Dear '.$customer_name.', your tracking number is ' .$tracking_number;
	
		return $return;
		
	}

}