Portland-based author Mary Robinette Kowal posed a challenge to the internet this month: Mail something every single day that the post office is open. "Write a postcard, a letter, send a picture, or a cutting from a newspaper, or a fabric swatch," she instructs on her website (lettermo.com). The project caught the attention of the New York Times and the Guardian, among others; we caught up with Kowal to ask her why she thinks, in an era of email, letter writing still captures the imagination.

"The nice thing about letters is that there's no expectation of instantaneous response," she says. "The things that I am writing are things that I expect will still be relevant in a week. It's nice to slow down; it is an almost physical and definitely mental thing, that the pace at which you write a letter is very different than the pace at which you use a computer. Writing letters forces me to be in the moment. You can't multitask while writing a letter."

Kowal has committed to responding to every letter that she receives—and if you write to one of her fictional creations, she'll respond in character. (Her debut novel Shades of Milk and Honey is a supernaturalized riff on Sense and Sensibility.) And as for writing letters to strangers: "You have to think about it like a conversation," she says. "If you think about it as writing for posterity, you're doomed. Which can be hard, because so much of our history has been recorded in letters—but if you actually go back and read the letters people wrote, a lot of it is just Jane Austen talking about the ribbons she's going to tie her bonnet with. These things are fascinating, but they're just minutiae of day-to-day life."