Letterlocking: The Hidden History of the Letter

Before the invention of the gummed envelope in the 1830s, how did people secure their private letters? The answer is letterlocking - the ingenious process of securing a letter using a combination of folds, tucks, slits, or adhesives such as sealing wax, so that it becomes its own envelope. In this book, Dambrogio and Starza Smith, experts who have pioneered the field over the last 10 years, tell the fascinating story of letterlocking within epistolary history, drawing on real historical examples from all over the world.

From Summer 2025 recommended reading from MIT (MIT News).