S.C. Code § 33-56-130
If a charitable organization, professional fundraising counsel, professional solicitor, or commercial co-venturer soliciting contributions from people in this State and having a principal place of business outside the State, or organized under and by virtue of the laws of a foreign state, is subject to the provisions of this chapter and does not otherwise appoint a registered agent for service of process, that charitable organization, professional fundraising counsel, professional solicitor, or commercial co-venturer is considered to have appointed irrevocably the Secretary of State as an agent upon whom may be served summons, subpoena, subpoena duces tecum, or other process directed to the charitable organization, professional fundraising counsel, professional solicitor, or commercial co-venturer or a partner, principal officer, or director of it in any action or proceeding brought pursuant to this chapter. Service of process is made by delivering to and leaving with the Secretary of State, or with any person designated to receive service at the office of the Secretary of State, duplicate copies of the process, notice, or demand. The service is sufficient service if notice of the service and a copy of the process are sent by the Secretary of State to the charitable organization, professional fundraising counsel, professional solicitor, or commercial co-venturer, by registered or certified mail with return receipt requested, at the address provided for in the registration form required to be filed with the Secretary of State pursuant to this chapter or, in default of the filing of the form, at the last address known to the Secretary of State. Service of process is complete ten days after the receipt by the Secretary of State of a return receipt purporting to be signed by the addressee or a person qualified to receive the registered or certified mail, in accordance with the accepted practices of the United States Postal Service or, if acceptance was refused by the addressee, ten days after the return to the Secretary of State of the original envelope bearing a notation by the postal authorities that receipt of it was refused.
S.C. Code § 33-56-130