WordPress at a glance
filter is not described

woocommerce_email_additional_content_(id) filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_email_additional_content_(id)', 'filter_function_name_2395', 10, 3 );
function filter_function_name_2395( $format_string, $object, $that ){
	// filter...

	return $format_string;
}
$format_string
-
$object
-
$that
-

Where the hook is called

WC_Email::get_additional_content()
woocommerce_email_additional_content_(id)
woocommerce/includes/emails/class-wc-email.php 372
return apply_filters( 'woocommerce_email_additional_content_' . $this->id, $this->format_string( $content ), $this->object, $this );

Where in WP core the hook is used WooCommerce

Usage not found.