Even the Romans hated to be left on read.
90AD-100AD ish - To Fabius Justus.
It is quite a long time since I had a letter from you. "Oh," you say, "there has been nothing to write about." But at least you might write and say just that, or you might send me the line with which our grandfathers used to begin their letters: "All is well if you are well, for I am well." I should be quite satisfied with so much; for, after all, it is the heart of a letter. Do you think I am joking? I am perfectly serious. Pray, let me know of your doings. It makes me feel downright uneasy to be kept in ignorance. Farewell.
-Pliny the Younger