woocommerce_email_subject_no_stock filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_email_subject_no_stock', 'filter_function_name_2477', 10, 3 );
function filter_function_name_2477( $subject, $product, $null ){
	// filter...

	return $subject;
}

$subject

-

$product

-

$null

-

Where the hook is called

apply_filters( 'woocommerce_email_subject_no_stock', $subject, $product, null ),

Where in WP core the hook is used WooCommerce