Don't Charge for Email

Tim Bray has proposed a micropayment system to combat spam. A central authority – he suggests the post office – would issue “stamps” for perhaps $0.01. Then, each email message, blog post, etc. would have to prove that it had been paid for by a stamp. This low cost, he suggests, would have little effect on most people, but would be fatal to spammers. I am an admirer of Tim’s blog, but I think he’s dead wrong: this is one of the worst ideas I’ve seen in some time1. There are two main problems, revolving around cost & access, and centralization & innovation.

Cost & Access

A penny for an email message may not sound like much for many people. But for the poor it could effectively ration Internet communication. A homeless job seeker might be able to afford the payment to send out a batch of resumes, but the cost is one more reason not to. In the third world, a penny an email could quickly start to look like real money. Tim says the cost is negligible; he, for example, wouldn’t send more than 100 messages a day. I beg to differ. Thirty dollars a month is the cost of a cell phone or of broadband Internet.

Furthermore, it would be extremely tempting for the agency issuing the stamps to raise the price to whatever the market would bear. The lobbying might be hard to resist: why not let the free market decide and charge what the service is worth? Markets are supposed to be good at allocating scarce resources. But stamps aren’t scarce: any profit obtained from selling stamps is the product of an artificial monopoly – a monopoly which could be expected to raise the price at every opportunity. Is there any sufficient argument for arbitrarily limiting email access based on wealth2?

Centralization & Innovation

There are two forms of centralization here. The first is the central authority which issues the stamps. It becomes a critical gateway for access to Internet communication. Such power is immediately ripe for abuse, e.g. by lobbying politicians for an increase in the stamp rate.

But there is a second, invisible form of centralization here. Software for sending, routing, and delivering messages now has to include the ability to create, pass on, and authenticate stamps. It must do this in conjunction with the central authority (which therefore has the ability to decide who can authenticate and who can’t). Worse, it complicates the software. As with most complexity, this insulates incumbents from challengers. Authors of Internet communication software would need greater expertise in order to deal with the stamp system, and added resources in order to implement support for it. This added cost might mean little to Microsoft, but for the lone hacker it might be enough to stop new software from being developed. This would likely fall especially hard on the open source community.

The added complexity likely also has compound and unexpected interactions with other parts of the Internet communication infrastructure. New uses for the technologies might never see the light of day because of conflicts with the stamp system.

Meanwhile, the cost of stamps (or even just the perceived cost) would affect behavior: users would start finding ways to minimize stamps, e.g. by using blogs or wikis instead of email, even where they are less appropriate3.

As I said, it’s a bad idea. I can’t imagine it will come to pass. My real concern is that we in the software community too often forget the burdens imposed by the costs and complexity of our technologies. As for splogs (spam logs), I suspect the long term solution is identity, which while it solves many more problems, shares many of the disadvantages of the stamp scheme.


1 Actually, I’ve seen the idea of small charges to email messages proposed numerous times as a way to combat spam. I have even thought it was a good idea. I was wrong too.

2 A thought-experiment bears this out. What if the market were more democratic. Say every person was assigned 100 stamps per day for free. This would preserve access for the poor. But it is immediately obvious that some people would have a legitimate need for more stamps.

3 Updated (minutes later): Of course Tim is proposing that only end-user recipients would reject unstamped communications. So what I had written doesn’t apply: “Inevitably, I suspect, an independent communication system would arise – one not reliant on the stamp infrastructure. At this point, only draconian legislation or arbitrary control by ISPs – limiting technologies and their uses – could save the system.” Of course, ISPs might start requiring stamps in which case a parallel infrastructure is entirely possible.