S.C. Code Ann. § 23-9-80: Service of order or penalty assessment.

The service of any order or penalty assessment as provided in this chapter shall be made by either delivering a true copy to the occupant or owner personally, or by registered or certified mail directed to the last known address of such parties, and, in case of service by mail, affixing a copy thereof in a conspicuous place on the door to the entrance of the premises.