506.240.  Service of process. — 1.  Service of process under sections 506.200 to 506.320 shall be made by delivering a copy of the summons, with a copy of the petition attached, to the secretary of state of Missouri at his office, or in his absence, to the chief clerk of the secretary of state, at his office, and such service shall be sufficient service upon such nonresident.

  2.  The secretary of state shall immediately mail to the defendant, and to each of them if there be more than one, by restricted, registered mail, addressed to the defendant at his last known address, residence or place of abode a notice of such service and a copy of such process and petition.