What kind of law is it against the law to casually open someone else s envelope

Privately dismantling other people's letters is an illegal act that violates the administration of public security, and may be detained for up to five days or fined up to 500 yuan. If the circumstances are serious, it will constitute a criminal offense.

Legal basis: Article 48 of the "Public Security Administration Punishment Law" Whoever fraudulently receives, conceals, destroys, opens or illegally inspects the mail of others shall be detained for up to five days or fined up to 500 yuan.

Article 200 of the Criminal Law: Article 52 [Crime of Infringing on Freedom of Communication] Concealing, destroying, or illegally opening other people's letters, violating citizens' right to freedom of communication, and the circumstances are serious, is to be sentenced to up to one year imprisonment or short-term detention.

Article 253 [Crime of Opening, Concealing, or Destroying Mail or Telegraphs Without Permission] Postal workers who open or conceal or destroy mail or telegrams without permission shall be sentenced to fixed-term imprisonment of not more than two years or criminal detention.

Where property is stolen while the crimes in the preceding paragraph are committed, it is to be convicted and given a heavier punishment in accordance with the provisions of article 264 of this Law.

In any of the following circumstances, a case shall be filed for concealment, destruction or illegal opening of other people's letters, violating citizens' right to freedom of communication; 1. Concealing, destroying, or illegally opening other people's letters, with a large number of times or a large number; 2. Concealing, destroying, or illegally opening other people's letters, causing serious harm to others' work or life, or serious physical or mental damage; 3. Illegally opening other people's letters, altering the content of the letters, or publicizing the privacy of others, insulting the personality of others, or destroying the reputation of others; 4. Concealing, destroying, or illegally opening other people's letters, causing other serious consequences of repentance.

Legal basis: Criminal Law of the People's Republic of China

Article 253 Postal workers who open or conceal or destroy mail or telegrams without permission shall be sentenced to fixed-term imprisonment of not more than two years or criminal detention. Those who commit the crimes in the preceding paragraph and steal property from property are to be convicted and given a heavier punishment in accordance with the provisions of article 264 of this Law.

Illegal. Unauthorized opening of other people's letters is punishable as a crime of violation of freedom of communication. Where concealing, destroying, or illegally opening other people's letters, violating citizens' right to freedom of communication, and having any of the circumstances listed below, a case shall be filed; 1. Concealing, destroying, or illegally opening other people's letters, with a large number of times or a large number; 2. Concealing, destroying, or illegally opening other people's letters, causing serious harm to others' work or life, or serious physical or mental damage; 3. Illegally opening other people's letters, altering the content of the letters, or publicizing the privacy of others, insulting the personality of others, or destroying the reputation of others; 4. Concealing, destroying, or illegally opening other people's letters, causing other serious consequences of early blindness.