Could a One-Won Stamp on Every Email Kill Spam?

Opening

Hello, dear reader. Let me start with a question. Have you ever made an international call back in the 1990s? I remember the way people would jot down exactly what they wanted to say before picking up the phone, because the meter was ticking at hundreds of won per minute. Back then, we knew in our bones that communication had a cost.

What about now? Sending a single email costs, in practice, nothing. Same for texts, same for messaging apps. But the landscape this “free-ness” has produced is strange. As of 2025, roughly 376 billion emails circulate the globe every day, and nearly half of them are spam. Even more striking: a majority of that spam is now written by AI.

Here’s the core of today’s story. When sending a message costs zero, the recipient’s attention becomes a zero-cost resource too. And what it might take to reverse this could be surprisingly simple.

Free Messages Have Created a “Tragedy of the Digital Commons”

Economics has a concept called the “tragedy of the commons.”¹ On an open pasture shared by everyone, if each herder grazes as many cattle as possible, the grass eventually disappears and no one can use it anymore.

The email inbox follows exactly this structure. Since sending costs the sender nothing, it’s rational for marketers and spammers alike to send as much as possible. As a result, the recipient’s inbox has become a pasture stripped bare.

Korea’s situation is no different. According to a joint survey by the Korea Communications Commission and KISA (Korea Internet & Security Agency), the average monthly volume of illegal spam received per person hit a record high of 16.34 messages in the first half of 2024. After the government rolled out a strong comprehensive countermeasure, that number dropped to 11.60 in the second half — but the data for the first half of 2025 reveals an even more interesting pattern. Text-message spam plunged 58.5% to 3.04 messages per month, while voice spam actually rose about 40% to 2.13 messages per month.

Lock the door, and they come through the window. Economists call this the “balloon effect” — as long as the zero-cost structure of sending remains unchanged, spam simply switches channels and keeps going.