An almanac published 80 years ago, in the 25th year of the Guangxu reign of the Qing dynasty, notes that "day selection" service was available by mail. This tells us that China already had reasonably effective postal services, and also that the almanac producers were sharp businessmen.
相隔八十餘年的光緒二十五年通書，出現了郵寄擇日，顯然當時中國已創辦郵政，並被繼成堂這種反應敏銳的「民間企業」充分利用。