Legal analysis: 1. Lawyer's letter is a warning. Generally, the obligee entrusts a lawyer to send it to the infringer, asking the infringer to stop the infringement and compensate the obligee for the loss.

2. After receiving the lawyer's letter, try to check the products produced and sold by yourself against the infringement mentioned in the letter. If there is any infringement, it is best to actively contact the obligee or the opposing lawyer for negotiation.

3. If it is a legitimate product, you can provide a sales contract and a supply list. If you don't know that it is an infringing product, you can stop selling it.

Legal basis: Article 57 of the Trademark Law of the People's Republic of China commits any of the following acts, which are all violations of the exclusive right to use a registered trademark:

(1) using the same trademark as its registered trademark on the same commodity without the permission of the trademark registrant;

(2) without the permission of the trademark registrant, using a trademark similar to its registered trademark on the same commodity, or using a trademark identical to or similar to its registered trademark on similar commodities may easily lead to confusion;

(3) selling goods that infringe upon the exclusive right to use a registered trademark;

(4) Forging or unauthorized manufacturing of registered trademark marks of others or selling forged or unauthorized registered trademark marks;

(5) changing its registered trademark without the consent of the trademark registrant and putting the goods with the changed trademark on the market again;

(6) intentionally providing convenient conditions for the infringement of the exclusive right to use a trademark of others and helping others to commit the infringement of the exclusive right to use a trademark;

(7) causing other damage to the exclusive right to use a registered trademark of others.