This letter is posted December 24th 1939 to the shipping company A. P. Møller (to day Maersk) in Copenhagen from The Royal Danish consulate in Rangoon, Burma.
It could wonder that the stamps are perforated with the initials E.A.C. East Asiatic Company, another famous Danish shipping company. But there is an explanation, The manager of East Asiatic Company in Burma was Carl A. K. von Castonier, who also was the Danish honorary consul in Rangoon from 1936 until the beginning of WWII