During the seventeenth century, civility was highly standardized: that the epistolary rhetoric of the time also obeyed codes does not come as a surprise. Being an excessively expansive mother, Mme de Sévigné at first seems to escape them. These showing excesses yet meet in every respect with the codes spelled out in the textbooks, as the article highlights drawing on the professions of gratitude. Their three parts are the three key elements of any thank-you letter: (1) expressions of joy and sensitivity; (2) the praise for the benefits received; (3) the assurance of an eternal gratitude (which itself comes in three “places”). Neither originality nor conformism can be inferred. Rather, Mme de Sévigné’s correspondence illustrates the considerable leeway afforded by rhetorical models.