(A) Complaints or orders issued by the Code Enforcement Official pursuant to this chapter shall be served upon persons either personally or by registered or certified mail so long as the means used are reasonably designed to achieve actual notice. When service is made by registered or certified mail, a copy of the complaint or order may also be sent by regular mail. Service shall be deemed sufficient if the registered or certified mail is refused, but the regular mail is not returned by the post office within ten days after the mailing. If regular mail is used, a notice of the pending proceedings shall be posted in a conspicuous place on the property affected.
(B) If the identities of any owners or the whereabouts of persons are unknown and cannot be ascertained by the Code Enforcement Official in the exercise of reasonable diligence, and the Code Enforcement Official makes an affidavit to that effect, the serving of the complaint or order upon the owners or other persons may be made by publication in a newspaper having general circulation in the town at least once no later than the time at which personal service would be required under this chapter. When service is made by publication, a notice of the pending proceedings shall be posted in a conspicuous place on the property affected.