Louisiana Code of Civil Procedure Tit. VIII, Art. 4543. Service upon defendant and notice to interested persons

A. Service of the citation and petition shall be personal. Nevertheless, if the defendant is domiciled in this state, but is located elsewhere, service may be made by the delivery of a certified copy of the petition, citation, and all attachments, to the defendant personally by any person over the age of eighteen years. Service is effective as of the date a notarized affidavit is filed into the record affirming the personal delivery. Failure to serve the defendant as provided in this Paragraph shall preclude the court from granting the relief sought in the petition.

B. Within three days of filing the petition, the petitioner shall mail a copy of the petition by certified mail, return receipt requested, to the last known address of each other person named in the petition. Failure to mail a copy of the petition to any such person shall not affect the validity of the proceeding, but may subject the petitioner or his attorney to sanctions.