The article discusses the key role of etiquette function in epistolary genre. The author analyses means of speech etiquette in the 1702 epistolary heritage of G. W. Leibniz with an emphasis on forms of address. The formal/informal address (du/Sie), use of titles and epithets of respect areexamined, as is Courtoisie, i.e. prescriptive code for the opening and closing paragraphs in letters. Leibniz's letters areused to exemplify features of epistolary genre in the Early New High German period.