Is the testimony of an unknown person accepted?

Question:
He says: Some people with weak souls resort to sending malicious complaints and reports under a pseudonym, or signed "a good doer," against some officials or others who are strict in establishing the truth. And it has come in the Noble Qur'an: the verse [Al-Hujurat: 6], and the noble commands that align with the rulings of the pure Shari'ah do not accept such claims; because their objectives are clear and their intentions are known. So we ask your Eminence to give advice and clarify the religious aspects of such complaints signed "a good doer" or under a pseudonym.

Answer:
The principle is that the testimony of one who does not name himself is not accepted, and his statement is not accepted; because he may be an open sinner, and he may have a bad intention. And I have heard the verse: , so he is not relied upon if he says: So-and-so did such-and-such, or: So-and-so said such-and-such, or: So-and-so left such-and-such. He is not relied upon until he identifies himself, testifies, and the legal proof is established regarding the person.
But if the one who wrote the advice is an advisor or a good doer who reports on an action that took place in the institution, or took place in the office, then it is obligatory for the office manager to whom it was written to look into the matter; because this writer may be—as he said—an advisor, but if he named himself, he would be harmed. So if he says: In the office, such-and-such happened, or: In such-and-such department, such-and-such and such-and-such are happening, then it is obligatory for the one to whom it was written to look into the matter: Is it true? A good doer tells you: The employees in your office do not pray, they do not perform their work, they harm the visitors, fear Allah, hold them accountable, look into the matter: Is it truthful? Do not make an excuse merely because he did not name himself and neglect it. No, if he had named himself, perhaps you would have harmed him and the one to whom it was written would have been harmed, and he may be an employee as well.
So if the writer who did not name himself is an advisor who wants the official to look into the matter, and he did not say: So-and-so, son of so-and-so, but rather it is said: Look, in your office such-and-such and such-and-such are happening, in your department such-and-such and such-and-such are happening, then it is obligatory for you, O official—whether the office manager or the dean of the office or such— to look into those to whom the matter is attributed. Those who are said not to pray are looked into, those who smoke are looked into, those who neglect cases and letters are looked into, those who harm and insult the visitors are looked into. Do not make an excuse that he did not name himself and that is all. Fear Allah and look into what he told you and advised you about, even if he did not name himself. But if he says: So-and-so does such-and-such, and he named a specific person, do not obey him in that until you look into the matter and know whether he is truthful or not truthful in it? He says: So-and-so does not pray, and he is with you in the office. Look into whether he prays or does not pray? Instruct the people who are with you: Look, does he pray or does he not pray? Does he smoke or does he not smoke? And you are prohibited in the administration from smoking. Look at what he said, and do not rely on it. You do the other causes. And as for taking it as a crutch—that he did not name himself—so that you waste the matter, no, this is a mistake.