A great many words have been written on the subject of e-mail spam. Effort has been poured into all kinds of technological measures against it. In my view, many of these efforts have been a waste of time, because they have failed to address the fundamental problem of spam.
To explain my thinking, I’ll start with some basic statements:
Your attention is a valuable resource. If you doubt this, you need only look at the amount of money spent on advertising in an attempt to acquire your attention.
Therefore, your inbox is a valuable resource. Many people, perhaps most people, now check e-mail multiple times a day. In fact, according to some surveys college students spend more time on the Internet than watching TV. They check their e-mail inbox more than they look at ad breaks.
SMTP e-mail allows anyone to send mail. There’s no centralized registration required in SMTP; there’s no control over the growth of the SMTP e-mail network. While some servers restrict which SMTP clients may connect to them, there’s essentially no control over who sends mail, as it’s always possible to open a new web e-mail account, buy a new ISP dial-up account, or whatever.
SMTP e-mail is free for the sender. Sure, many people pay for their Internet access; but once you have an Internet connection, sending e-mail basically doesn’t cost you anything—it has marginal cost.
Now, let me re-cast those four statements:
We have unrestricted access for anyone in the world to use arbitrary amounts of a valuable resource.
Can you think of any case where there has been a system like that, and it has worked? I can’t. The canonical example is the tragedy of the commons, but there are plenty of others, including the Cambridge ‘Green Bike’ scheme and the overfishing of cod.
In order to avoid a “tragedy of the commons” situation, we need to alter the situation so that one of the statements above is no longer true. Let’s go through them again and consider our options.