Tenn. Code Ann. § 45-2-606

Any bank may, for the convenience of its customers, provide suitable receptacles on, in, or as a part of the bank premises for the deposit of money, checks and other property, and may contract with its customers, through display of appropriate notice upon the receptacles or by written notice to its customers, that the receptacles are instrumentalities of the customer and that money, checks or other property placed in them shall not be considered to be deposited with the bank until received by an employee or officer of the bank. The receptacle shall not be placed in or located on, in or about any premises where the bank cannot legally carry on the business of banking.