Tenn. Code § 12-4-205
Such furnisher of labor or material, or such laborer, to secure the advantage of §§ 12-4-201 - 12-4-206, shall, after such labor or material is furnished, or such labor is done, and within ninety (90) days after the completion of such public work, give written notice by return receipt certified mail, or by personal delivery, either to the contractor who executed the bond, or to the public official who had charge of the letting or awarding of the contract; such written notice to set forth the nature, an itemized account of the material furnished or labor done, and the balance due therefor; and a description of the property improved. In the case of public work undertaken by a municipality, or any of its commissions, notice, or statement herein required, so mailed or delivered to the mayor thereof, shall be deemed sufficient. In the case of public work by any county or any of its commissions, notice or statement herein required, so mailed, or delivered to the county mayor of such county, shall be deemed sufficient. In the case of public work by the state, or any of its commissions, notice and statement herein required, so mailed, or delivered to the governor, shall be deemed sufficient.
T.C.A. § 12-4-205