Without the teacher's consent, posting letters to the Education Bureau on public platforms such as Baidu Post Bar may violate personal privacy, reputation and other issues, so it may be illegal.

In China, according to the provisions of the Civil Law of People's Republic of China (PRC) (PRC), everyone should respect the personal dignity, reputation, privacy and other basic rights of others, and should not maliciously slander others through public channels such as the Internet and social media. In addition, according to the Cyber Security Law of the People's Republic of China, individuals should protect their personal information in accordance with the law and must not disclose other people's personal information without authorization.

Therefore, if you want to report a teacher, I suggest you consult relevant laws and regulations first and report through legal channels to avoid legal risks caused by improper words and deeds.