woocommerce_email_content_backorder │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_email_content_backorder', 'wp_kama_woocommerce_email_content_backorder_filter', 10, 2 );

/**
 * Function for `woocommerce_email_content_backorder` filter-hook.
 * 
 * @param  $message 
 * @param  $args    
 *
 * @return 
 */
function wp_kama_woocommerce_email_content_backorder_filter( $message, $args ){

	// filter...
	return $message;
}

$message

-

$args

-

Where the hook is called

apply_filters( 'woocommerce_email_content_backorder', $message, $args ),

Where the hook is used in WooCommerce