CentMail: Do Good, Fight Spam

Saturday, August 15, 2009
By dreeves


Our anti-spam project, Centmail, has gotten some press this week. (New Scientist, ABC News, Wired, Slashdot, Hacker News.) In a nutshell, you donate a penny to a charity of your choice for every email you send, with the donation showing up as a “stamp” in your email signature. Since spammers can’t afford to pay even just one cent per message, these CentMail-certified donations help distinguish humans from bots. The reaction is not wholly positive.  “I wouldn’t donate belly button lint for this lunacy,” says one commenter.  Says another: “Charging per email is a stupid idea, and must have been thought up by someone with not enough real work to do.”  Fair point, that last one. (It was Sharad‘s idea!) Of course CentMail is not exactly about charging for email. Still, many people have a strong aversion to mixing email and money, no matter how benignly. Plus there’s some cynicism about Yahoo‘s motives (it’s not like that, we swear!).

We’ve put up a CentMail FAQ in hopes of clearing up some misconceptions. For the nitty-gritty details, check out our technical paper.

(PS: More on John Langford’s blog, hunch.net.)


CentMail was created by Sharad Goel, Jake Hofman, John Langford, David Pennock, and Daniel Reeves, with design and engineering help from Tom Gulik, Tom Maher, and Sergiy Matusevych.

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  • http://www.openmuseum.org Jeff Doyle

    Your frequently asked questions says that you will provide a list of eligible charities. I assume that any legitimate 501c3 organization is eligible but how do we get on the list?

  • http://ai.eecs.umich.edu/people/dreeves dreeves

    Thanks for asking! We’ll be in touch…

  • http://sites.google.com/site/gparker/ Gordon Rios

    Haha, brilliant! Like the inverse of a “safelist” … let the real email senders pay to charity in order to self-identify. Email clients already do network lookups for Real Time Bl(o)cklists to filter out some of the spam traffic but the Safelist has always been problematic since it required the receiver to be precognitive in order to pass through new senders.

  • Alistair Jardine

    I wonder Will it available for Great Britain? (Pennymail)
    and benefit British Charity’s.?

  • pch65

    I wonder will it available for all countries ?
    I’m living in France.

  • Vishal

    check out boxbe [http://www.boxbe.com]. Thede should be able to supply underlying academic work…

  • Daniel Carrera

    I read the technical paper and the FAQ. CentMail sounds really promising. I’m very excited about it. Will it be available in other countries? Will I be able to select non-US charities? (e.g. Oxfam in the UK).

  • http://ai.eecs.umich.edu/people/dreeves dreeves

    Thanks Vishal, we do cite the paper by Thede Loder et al in our technical paper. And I’m a fan of boxbe, too.

    Thanks everyone else for all the interest in CentMail! We’re not sure about any specific charities but hope to have some with international appeal when we launch. Nothing else about CentMail precludes international users.

  • http://daniel.carrera.bz Daniel Carrera

    Any idea when you’ll launch? I think CentMail is a brilliant idea. In addition to all the spam-fighting reasons, I think CentMail has the potential to get people thinking about charity. In particular, research shows that people are more willing to donate to charity if they realize that other people are donating too. So CentMail might actually do a lot of good for the poorest people in the world. That’s a nice win-win: Reduce spam, increase charitable giving. I love it!

    When will you launch?