Customs may not be able to find out, because only the name of the exported goods needs to be provided when declaring to the customs. After your trademark is put on record, the customs will ask other similar goods to provide the trademark name or trademark use authorization when exporting, but it is impossible for the customs to check and verify the authenticity of each ticket, so it can only check the goods at a certain inspection rate.

In fact, after the trademark is filed in the customs, it can not prevent others from counterfeiting, but it can play a warning role. In addition, if the customs is required to detain other people's counterfeit goods without filing, the trademark owner needs to pay a deposit equivalent to the seized goods, otherwise the customs has the right not to cooperate. Now, after filing with the customs, the customs will cooperate with you only if you propose to detain other people's goods, and of course you will bear the consequences.