The hook woocommerce_email_order_details has 4 parameters which can help you to identify the correct message. add_action( ‘woocommerce_email_order_details’, ‘so274215_add_transaction_id’, 10, 4); function so274215_add_transaction_id( $order, $sent_to_admin, $plain_text, $email ){ // decide here wether to show your transaction id if ( ! $sent_to_admin ) echo ‘<span style=”color:#555;font-size:1.5em;”>Transaction ID: ‘.get_post_meta( $order->id, “_transaction_id”, true ).'</span>’; } As far as I … Read more