Haw. Rev. Stat. § 634-38: Manner of service within the State; assumpsit.

For civil actions in the nature of assumpsit, when service of summons is required by law, court rule, or court order, service on the defendant within the State shall be:

(1) By personal delivery by a person authorized to serve process; or

(2) If a reasonable attempt at personal delivery has not been successful, then by certified, registered, or express mail sent to the addressee only, as ordered by the court.

Service pursuant to paragraph (1) and proof of personal service shall be made in the manner prescribed by law, court rule, or court order. If service is made pursuant to paragraph (2), a return receipt or other proof of service provided by the postal service shall be filed showing delivery to the addressee within the State.