Regulations Governing the Handling of Mail Article 40

In the event that a mail contains any document or material prohibited to be mailed, or is not posted in accordance with regulations, the sender shall bear the responsibility.If the mail consequently causes damage to Chunghwa Post or other mails, Chunghwa Post may file a claim against the sender.Although the mail item has been accepted for delivery by the post office, the sender is still liable.
中文原文 郵件處理規則第40條
寄件人應承擔郵件因內裝有禁寄之文件、物品或不依規定交寄之責任,如致中華郵政公司或其他郵件受有損害者,該公司得向寄件人請求賠償。
郵件雖經郵局收寄,寄件人仍不免除前項責任。

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