Regulations Governing Customs Clearance Procedures for Importing and Exporting Postal Parcels Article 4

The place for the storage and for customs clearance procedure of postal articles shall be provided by the postal authority and approved by Customs. The examination spots, movement lines and other necessary facilities shall also meet the requirements for customs examination and clearance.The warehouse for the storage of postal articles under the preceding paragraph shall be jointly locked by both the postal authority and Customs.
中文原文 郵包物品進出口通關辦法第4條
郵包物品存儲及辦理通關作業所需之通關場所應由郵政機構提供並經海關核准。
其查驗場地、動線及其他必要設施並應配合海關查驗及辦理通關之需要。
前項存儲郵包物品之倉間應由郵政機構及海關共同聯鎖。

English translation for reference only; the Chinese text prevails. Not legal advice.