Regulations Governing the Safe Transport of Dangerous Goods by Air Article 29

Dangerous goods shall not be introduced into air transport through postal services, nor shall dangerous goods be concealed in any air mail unless they are offered for air transport in accordance with the Technical Instructions and the Regulations Governing the Handling of Mail.
中文原文 危險物品空運管理辦法第29條
危險物品不得以航空郵件交運或於航空郵件內夾帶危險物品。
但依技術規範及郵件處理規則之規定交運者,不在此限。

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