Legal analysis: Yes, as long as the creditor has signed a letter of entrustment with the law firm (including the creditor's perennial legal consultant firm), it is completely legal for the law firm to send a lawyer's letter for dunning.

legal basis: article 577 of the civil code of the people's Republic of China

if a party fails to perform its contractual obligations or fails to perform the contractual obligations in conformity with the contract, it shall bear the liabilities for breach of contract such as continuing to perform, taking remedial measures or compensating for losses.

article 578 if one party expressly indicates or indicates by its own behavior that it will not perform its contractual obligations, the other party may request it to bear the liability for breach of contract before the expiration of the performance period.

article 579 if one party fails to pay the price, remuneration, rent or interest, or fails to perform other monetary obligations, the other party may demand payment.