Legal analysis: the contract signed by mail is valid. A contract has the following three effective elements: 1, and the actor has the corresponding contracting ability; 2. The meaning is true; 3. It does not violate mandatory laws or social public interests. In this case, the contract signed by mail is valid as long as it has the effective elements of the contract, that is, the actor has the corresponding contracting ability, the intention is true, and the contract content does not violate mandatory laws or social public interests.

Legal basis: Article 493 of the Civil Code of People's Republic of China (PRC). Where the parties conclude a contract in the form of a contract, the place where the contract is established is the place where the parties finally sign, seal or print, unless otherwise agreed by the parties.

Article 491 The parties entered into a contract in the form of data messages. It is also required to sign a confirmation letter, and the contract is established when the confirmation letter is signed.