Legal analysis: In principle, a contract without a signature or seal will not be effective, and exceptions are also provided, that is: a contract is concluded in the form of a contract including a confirmation letter, and before signing or sealing, one of the parties has already If the main obligations are fulfilled and the other party accepts them, the contract is established. This avoids the lack of formal requirements from impairing the validity of the contract, which not only conforms to the interests of the parties, but also promotes the circulation of the commodity economy.

Legal basis: Article 490 of the "People's Republic of China and Civil Code" Where the parties conclude a contract in the form of a contract, the contract is established when both parties sign, seal or fingerprint. Before signing, sealing or fingerprinting, one party has performed its main obligations and the contract is established when the other party accepts it.

Laws, administrative regulations or the parties agree that a contract should be concluded in writing. If the parties do not do so in writing but one party has performed its main obligations and the other party accepts it, the contract is established.