Postal Act Article 7

Apart from Chunghwa Post or those it has authorized, no others may use the same words, graphics, symbols or combinations thereof (both in Chinese and foreign languages) that Chunghwa Post uses to display its business titles, services or products.
中文原文 郵政法第7條
除中華郵政公司或經其同意者外,任何人不得使用與郵政、郵局(含中文及外文)相同之文字、圖形、記號或其聯合式,表彰其營業名稱、服務或產品。

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