The clerk of the court shall also, on or before twenty days after the first publication, send a copy thereof by mail to such defendants who are not residents of the state whose place of address is known or stated in the application and whose appearance is not entered and who are not in person served with the summons. The certificate of the clerk that he has sent such notice in pursuance of this section shall be conclusive evidence thereof. Other or further notice of the application for registration may be given in such manner and to such persons as the court or any judge thereof may direct. The summons shall be served at the expense of the applicant, and proof of the service thereof shall be made as proof of service is now made in other civil actions.L. 03: p. 320, § 20a. R.S. 08: § 735. C.L. § 4945. CSA: C. 40, § 190. CRS 53: § 118-10-22. C.R.S. 1963: § 118-10-22.