N.D. Cent. Code § 32-19-22

The notice before foreclosure may be served by mail, as provided in rule 4 of the North Dakota Rules of Civil Procedure, addressed to the owner of record at the owner's post-office address in the mortgage or by the records in the chain of title of the recorder of the county where the real estate is situated. If the post-office address is not shown in the mortgage or in the records, the notice may be served as provided in rule 4 of the North Dakota Rules of Civil Procedure, addressed to the owner of record at the post office nearest any part or tract of the real estate.