Haw. Rev. Stat. § 271-26.5
A motor carrier shall have, maintain and operate from a definite place of business in the State and shall display therein the certificate or permit issued by the public utilities commission. The certificate or permit holder shall report any change of address or telephone number to the commission within five business days from the change. Communications, correspondence , service of orders, and other official documents shall be made upon the motor carrier, complainant, and any other party at the last recorded mailing or electronic mail address on file with the commission. Proof of service by certified or registered mail or by electronic transmission to the last known mailing or electronic mail address shall constitute a valid service of any commission's official document.
HRS § 271-26.5