Neb. Rev. Stat. §§ 52-2104
The commercial real estate broker shall, within ten days after recording its notice of lien, either mail a copy of the notice of lien to the owner of record of the commercial real estate by registered or certified mail at the address of the owner stated in the commission agreement on which the claim for lien is based or, if no such address is given, then to the address of the commercial real estate on which the claim of lien is based. Mailing of the copy of the notice of lien is effective when deposited in a United States mailbox with postage prepaid. The commercial real estate broker's lien shall be unenforceable if mailing or service of the copy of notice of lien does not occur at the time and in the manner required by this section.
Neb. Rev. Stat. §§ 52-2104