Paul Graham has published an article about fighting spam in August 2002. I his article "A Plan for Spam", he used to differentiate between Spam and Ham - nonSpam - using a statistical approach.

"I think we will be able to solve the problem with fairly simple algorithms. In fact, I've found that you can filter present-day spam acceptably well using nothing more than a Bayesian combination of the spam probabilities of individual words. Using a slightly tweaked Bayesian filter, we now miss less than 5 per 1000 spams, with 0 false positives", Paul Graham

The point is that do I really need all these mathematical calculations in order to decide whether that email is Spam or not? Most of the time I can tell if an email is spam using the sender's email address. I know that email addresses can be forged using open SMTP relays etc. So what I am thinking of is that we can use the PKI (Public Key Infrastructure) combined with the Email Servers in order to differentiate between Spam anb Ham.
Organizations as well as ordinary users are supposed to get a Digitical Certificate stating that they are not spammers. These certificates can be obtained from the current CAs (Certificate Authorities) such as VeriSign, Thawte, etc or new entities can be formed for such purpose. These CAs has to be supervise by some organization to decide if they really give Digitat Certificate to non spammers only or not. Users shall sign their Emails with their own Private Keys and Mail Servers are supposed to accept mails that are signed only.
Source:
http://gr33ndata.blogspot.com/2006/03/plan-for-ham.html

Tags: Email, Spam, Internet, PKI, Technology, Gr33n Data