In this part, delivery shall be made by:
(1) Personal delivery;
(2) Registered or certified mail with adequate postage to the recipient's address; provided that delivery shall be considered made three days after deposit in the mail or on any earlier date upon which the return receipt is signed;
(3) Facsimile transmission, if the recipient has provided a fax number to the sender; provided that delivery shall be considered made upon the sender's receipt of automatic confirmation of transmission;
(4) Electronic mail; or
(5) Any other way prescribed by the commission.