Correspondence refers to the friendly intercourse, especially the intercourse between people by means of letters. In the modern society, with the rapid development of the technology, telephone and email besides post letter have already become the most popular correspondence approaches both in our daily life and business occasions. When we use the traditional post or telecommunications to announce a special occasion, express thanks or just keep in touch, it is of great importance to pay attention to the details so that our message is conveyed the way we intended.