Is it valid to send a lawyer’s letter from the official WeChat account?

Legal subjectivity: It has legal effect. Issuing a lawyer's letter can serve as a legal proof and a de facto warning.

Legal objectivity:

Civil Code of the People's Republic of China

Article 165 If the power of attorney is in written form, the name of the agent shall be stated Name, agency matters, authority and term, and signed or stamped by the principal.

Article 919 An entrustment contract is a contract in which the principal and the trustee agree that the trustee will handle the principal's affairs.

Article 920 The client may entrust the trustee to handle one or several specific affairs, or may entrust the trustee to handle all general affairs.