189311月23日烟台寄本埠商业封, 无贴邮资, 盖稀缺蓝色无框 "TO PAY" 戳, 旁有"2" 字, 封贴盖蓝色㰐圆形烟台书信馆日戳, 相信是这种 "TO PAY" 邮戳的最早使用例.源流: 1992年9月Frederick and Timiko Bartlett, 2001年11月Charles Goodwyu. 欠资信封的应付邮资是邮费的两倍, 在这种情况下, 是一分的两倍.Chefoo Postage Due 1893 (23 Nov.) local commercial envelope, unfranked and bearing a good strike of the unframed "TO PAY" handstamp struck in blue with manuscript "<I>2" in pencil , the reverse with "<H>chefoo/local post" dated oval in blue. THis is believed to be the earliest example of this scarce mark. Photo
