N.C. Gen. Stat. § 44A-24.7: Lien claimant to mail copy of notice of lien to owner by certified mail.

Any lien claimant who files a lien on commercial real estate pursuant to the provisions of this Part shall mail a copy of the notice of the lien to the owner of the commercial real estate by certified mail, return receipt requested, or shall serve a copy of the notice of the lien in accordance with any of the provisions for service of process set forth in G.S. 1A-1, Rule 4. The lien claimant shall file proof of service with the clerk of the superior court. The lien is void if the lien claimant does not file and serve the lien as provided in this Part. (2011-165, s. 1.)