S.C. Code Ann. § 27-32-330
(A) In any foreclosure proceeding under this article, the trustee is required to notify the obligor including persons in this State, outside of this State, or in foreign countries by delivering a written notice of default and intent to sell under Section 27-32-325 to the notice addresses of the obligor and junior interest holders, as applicable, by certified or registered mail, as follows:
(B) If the certified or registered mail sent pursuant to subsection (A) is returned with an endorsement or stamp showing "refused", the trustee may send the notice by first class mail to the notice address. The failure to claim certified or registered mail is not refusal of notice within the meaning of this subsection. Notice pursuant to this subsection must be delivered as follows: