Legal analysis: the signature of fax has legal effect, and the legal effect is legally binding, which means that people must abide by the law if they want to act in accordance with the law. The general effective requirement of a contract is that the parties have the corresponding ability to conclude a contract. The meaning is true and does not violate the law and social public interests. Legitimacy is the essential attribute of civil juristic act, and it is also a necessary condition for the validity of civil juristic act.

Legal basis: Article 143 of the Civil Law of People's Republic of China (PRC) is valid for civil juristic acts that meet the following conditions: (1) The actor has corresponding capacity for civil conduct; (2) the meaning is true; (three) does not violate the mandatory provisions of laws and administrative regulations, and does not violate public order and good customs.