woocommerce_mail_callback_params │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_mail_callback_params', 'wp_kama_woocommerce_mail_callback_params_filter', 10, 2 );

/**
 * Function for `woocommerce_mail_callback_params` filter-hook.
 * 
 * @param  $array 
 * @param  $that  
 *
 * @return 
 */
function wp_kama_woocommerce_mail_callback_params_filter( $array, $that ){

	// filter...
	return $array;
}

$array

-

$that

-

Where the hook is called

$mail_callback_params = apply_filters( 'woocommerce_mail_callback_params', array( $to, wp_specialchars_decode( $subject ), $message, $headers, $attachments ), $this );

Where the hook is used in WooCommerce