Spam, Spam, Spam, Spam

I can’t imagine that anyone still reads email spam, so why do we still get so much of it? Imagine that it costs a penny to send one million spams. What is the Nash equilibrium of the spam game?

We can’t have spam equilibrium if some player regrets not sending spam. If the cost of sending one million spams were one penny, then a rational player would regret not spamming if it would earn her more than a penny. Consequently, game theory dictates that almost everyone must ignore inbox spam. If even 1 percent of the population regularly read their spam, then it would clearly be worthwhile for some retailer to spend a penny to reach 1 percent of a million users. Therefore if 1 percent of us read spam, more people will get spammed, which would reduce the number of spam readers. This process must continue until almost nobody reads the stuff.

How can we solve our spam dilemma? The best approach would be some technical fix that effectively separates out wanted email from spam. Email providers, however, obviously haven’t mastered this trick. It would be impossible to get all spammers to agree to reduce their output, for even if some did, it would increase the benefits of others to spam. Spamming would decrease if the cost to spammers could be raised, but increasing the cost is challenging. If we impose legal penalties on spammers, then we will attract overseas spammers beyond the reach of American law. We have currently reached spam equilibrium, so if Americans spam less, some Americas would get less sick of spam and read more of it, thus increasing the benefit of foreigners to spamming us. Absent some anti-spam war (spammers, the next Axis of Evil?), we are unlikely to get other countries to prioritize stopping international spamming.