Legal analysis: The contract can be signed by mail. If the parties conclude a contract in the form of a contract, the contract is established when both parties sign, seal or fingerprint the contract. Before signing, sealing or fingerprinting, one party has performed its main obligations and the contract is established when the other party accepts it.

Legal basis: "People's Republic of China and Civil Code"

Article 490: Where the parties conclude a contract in the form of a contract, both parties shall sign, seal or The contract is formed when the fingerprint is pressed. Before signing, sealing or fingerprinting, one party has performed its main obligations and the contract is established when the other party accepts it.