'Leak-Proof' Anti-Spam Solution?

sikandril asks: "In an effort to help the Internet community and user-base at large in fighting spam, I have decided to put up this white paper for public review and remarks. As you will see, the system provides an almost 'waterproof' solution to spam blockage via an opt-in system. The main drawback is that everyone (except spammers or other evildoers) has to have this installed in order for it to work perfectly. A small number of installs means that unknown legit contacts still might show up as spam, albeit only for the first e-mail and/or until they too elect to install the software. I'm an independent developer located in Israel, and would love to hear your ideas regarding this."