Saturday, May 1, 2010

Solving Email Congestion

Email costs zero to send but it consumes the attention of the recipient. The cost of attention is not charged to the sender, which can lead to too many messages being sent and inbox congestion. This is a kind of information pollution that is especially visible in the billions of spam messages sent each year.

In his blog today, Greg Mankiw argues that charging senders a small price to correct this externality is an appealing "Pigovian" solution. For instance, a reader of his blog writes:
[A] penny tax (say) on email would probably generate large amounts of revenue, mitigate an important negative externality, and have minimal inefficient disincentives. Since email servers are necessarily centralized and networked and all email senders are ipso facto connected to an ISP who is charging them for access the transactions costs and evasion problems seem low.

I agree that charging senders is the ideal way to solve the email congestion problem, especially spam. It is superior to technical solutions like filters because it helps align the sender and recipients' incentives and thereby harnesses the knowledge that the sender has about the content.

Unfortunately, the issues are a bit more complicated than he describes in his brief posting and thus this solution requires some new standards and infrastructure. Along with Marshall van Alstyne and Jon Koomey, I wrote an Op-Ed in the WSJ explaining some of these issues and proposing a way forward.

See "You've Got Spam" (WSJ, Sept 6, 2007).

Update: [Here's an un-gated version]


  1. Here's an interesting proposal in this vein from Yahoo! Research:

  2. Thanks, John. That's a terrific site. I've asked them to notify me when they launch.

    I hope they get the necessary critical mass. If they do, it might be easier for similar system to get off the ground.

  3. I'm not sure if it'll stop spammers.

    If spammers manage to sell things out of their spam or get anything that has economic value then the question would not be whether or not sending email should be charged, but how much should it be charged, because spammers can calculate a maximum cost per email sent in order to make spamming profitable.

    Indeed, I think spammers are the only ones willing to pay to send an email.