He did publicly recall receiving fan mail connected with men in prison.
The information came from a recent interview, not an invented meme or an anonymous social-media rumor.
What Needs Qualification
Cooper apparently did not read the letters himself at the time. His mother intercepted them.
Their contents have not been released, so headlines should avoid claiming that they contained specific threats, sexual messages or criminal plans.
It is also more accurate to say that Cooper “said” he received the correspondence. The existence of the letters has not been independently confirmed through publicly available documents.
Final Verdict
The viral claim is substantially accurate.
Justin Cooper said that, during his childhood fame, letters arrived from men who were incarcerated. His mother kept the correspondence from him and protected him closely while he worked.
The interview and quotation are authentic.
What remains unknown is the number of letters and precisely what they contained.
A careful headline would read:
Former Liar Liar child actor Justin Cooper says his mother shielded him from fan mail sent by men in prison during the height of his childhood fame.
That preserves the disturbing but verified core of the story without adding details Cooper did not reveal.