This letter is written in Chinese and mentions Ray [Huang Renyu 黄仁宇, historian Ray Huang]. It seems that she is the younger sister of Ray Huang, and wrote the third article in his book, 1587，A Year of No Significance: The Ming Dynasty in Decline [Chinese title: Wan li shi wu nian 万历十五年] (https://www.sto.cc/book-82999-1.html).