Look in this file /admin/recover_cart_sales.php

Around line 281 - 285 you find references to

"$html_msg['EMAIL_MESSAGE_HTML'] = nl2br($email) . zen_db_prepare_input($_POST['message_html']);" (for the HTML version)

zen_db_prepare_input($_POST['message']) (for the 'text version)

You can take those lines and do what you want with them.