1){$customer_name} -  To display the order followup email greeting.

The data of this can be change by changing the value of define ORDER_FOLLOWUP_EMAIL_GREETING from the admin url system/admin/language_variables.php?page=1&fID=admin_defines&action=edit

2){$email_text_last} – To display the order follow up email text.

The data of the order followup email text can be change by changing the value of define ORDER_FOLLOWUP_EMAIL_TEXT  from the admin url

system/admin/language_variables.php?page=1&fID=admin_defines&action=edit

3) {$customer_orderproducts_qty_name} – To display description about the ordered products like products quantity, product name.