[hashcash] Re: PR Problem?

Todd A. Jacobs wrote:

I think a whitelisting demon might or might not be valuable, depending
on how one uses the stamps. Where it probably has the most value is
either on the sending side (cheaper or no stamps based on the status of
the recipient), or on the MTA side where saving CPU cycles on
trusted-but-high-volume senders/recipients might be valuable.
Well, on the recipient side I use it to further bypass any content analysis. Works well, haven't had any leaks because it's virtually impossible for the spammer to find out which source addresses pass through without analysis
the other advantage to white listing based on addresses is that provide you with some benefit to those not using a proof of work system. This gives people further reason to adopt your system instead of sticking with the same old same old.
Stamps provide benefit in the future, white listing provides benefit to all you speak with now, and the combination is compatible with the past. 


In a naive sender-pays setup, I'm not sure that the cost of validating
received stamps is high enough to justify inbound whitelisting. And
because the selling point to the end-user is that minting stamps makes
your email look more like ham, I don't see how whitelisting your
recipients from the sender side (e.g. not minting stamps for friends) is
a win.
yes, with a naïve system, white listing has no advantage if you think of it in terms of stamp users only.
The rest of your points boil down to philosophical differences. I will not perform content analysis on a message that has either passed with a stamp or white lists. I prefer always pass because there are no false positives. Between stamps and white lists, I would never need to look into the dumpster/spam trap.
Think about the difference between always pass versus score fudging. with score fudging, you are moving the goalposts in favor of messages with stamps. But you are also moving them for messages with spam. I wish I could tell you were the threshold for good versus bad stamp size would be for this model but I haven't figured out the equation yet. I know with always pass, an unknown number of zombies, the stamp size should be around 90 seconds in order to leak only 10% of the traffic.
But this little number also highlight something else about stamps which is that it always pass, how much you leak is the total volume of spam on the net (assuming everybody is generating stamps). We would need to do similar modeling to find out how much we can reduce spam traffic using the score fudging technique. 




In a more complex scheme, though, that would probably be very valuable.
How do you envision the whitelisting working?
it's real simple. it would be used for three things. The simple white list takes an e-mail address and a user identifier and yields a Boolean saying whether or not this user was listed. A variant would say that the domain was listed if the user could not be found.
The next variant would use the IP address and yield either a postage requirement or a quality score which could be used to determine whether to blacklist the address or not. 

a simple implementation is relatively easy, a fast one is not.

---eric

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