Mo. Rev. Stat. § 506.340
Current with changes from the 2023 Legislative Session
Service shall be made by mailing a copy of the original summons to the secretary of state, and such service shall be sufficient; provided that a copy of the service shall be forthwith sent by registered mail to the defendant and the defendant's return receipt and an affidavit of plaintiff or his attorney as to compliance herewith are filed in this action.
§ 506.340, RSMo