Push Systems vs Pull Systems
adam.blog.heroku.com
adam.blog.heroku.com
This idea is an authentication-based system, because it relies on identifying the message sender in order to prevent spam. Among other things, it fails to account for identity theft.
For reference, here is my thesis: http://www.eecs.harvard.edu/~cduan/download/?file=thesis.pdf
And in short:
(X) users of email will not put up with it
(X) requires immediate total cooperation from everybody at once
(X) many email users cannot afford to lose business or alienate potential employers
specifically, your plan fails to account for:
(X) extreme profitability of spam
(X) joe jobs and/or identity theft
(X) extreme stupidity on the part of people who do business with spammers
(X) dishonesty on the part of spammers themselves
(X) outlook
and the following philosophical objections may also apply:
(X) whitelists suck
I would like to conclude that this is not some snarky elitist comment to this insightful blog post. I'm simply stating that spam is a very old problem, and many people have spent a lot of time trying to stop it. This form exists as a reminder that many of these options have been thought up before, tried, and found to fail. We've learned from some of our mistakes :)
Spam is "profitable" because of the low cost of spamming a bunch of random people at once. I think the article is making the point that there are alternative low-cost solutions which can be targeted more precisely to an audience that is actually interested in the source of the "spam," thus making it much less annoying.
"The primary motivation behind the protocol was providing deniability for the conversation participants while keeping conversations confidential, like a private conversation in real life, or off the record in journalism sourcing. This is in contrast with the majority of cryptography tools which resemble more a signed writing on paper, which can be later used as a record to demonstrate the communication event, the participants, and the topic of communication. In most cases people using ordinary cryptography software are not aware of this and might be better served by OTR tools instead. The initial introductory paper was named "Off-the-Record Communication, or, Why Not To Use PGP"."