woocommerce_email_downloads_columns filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_email_downloads_columns', 'filter_function_name_833' );
function filter_function_name_833( $array ){
	// filter...

	return $array;
}

$array

-

Where the hook is called

$columns   = apply_filters(
	'woocommerce_email_downloads_columns',
	array(
		'download-product' => __( 'Product', 'woocommerce' ),
		'download-expires' => __( 'Expires', 'woocommerce' ),
		'download-file'    => __( 'Download', 'woocommerce' ),
	)
);

Where in WP core the hook is used WooCommerce