26. Service is made by sending the summons to the person for whom it is intended, at his last known residential or business address, by registered or certified mail, with an acknowledgment of receipt or a notice of delivery.
Such service is deemed to have been made on the date on which the acknowledgment of receipt was signed by the person for whom it is intended or any reasonable person living at his residence or in charge of his place of business, in the case of registered mail, or on the date of the notice of delivery in the case of certified mail.