WordPress at Your Fingertips
filter is not described

woocommerce_email_subject_backorder filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_email_subject_backorder', 'filter_function_name_6968', 10, 3 );
function filter_function_name_6968( $subject, $args, $null ){
	// filter...

	return $subject;
}
$subject
-
$args
-
$null
-

Where the hook is called

WC_Emails::backorder()
woocommerce_email_subject_backorder
woocommerce/includes/class-wc-emails.php 707
apply_filters( 'woocommerce_email_subject_backorder', $subject, $args, null ),

Where in WP core the hook is used WooCommerce

Usage not found.