It makes sense to pull the burden of overcoming spam off users backs and shift the responsibility for spam to senders. I agree that a white-list system with embedded document signatures is a step in the right direction. Only dont stop at e-mail; use a white-list registration scheme for all Internet users, with embedded signatures required in every document on the Internet, including Web pages, e-mail and images—everything.
In such a system, every user would have to supply valid, instantly verifiable credentials to access or create documents. Document signatures would be categorized by type, from a default general category for everyday use to specific types, such as for marketing, organizations or porn. Filtering would then be straightforward—by category only—with no need for complex content filtering. The benefits could extend much further to the more serious problems of viruses and worms.
If each document transmitted over the Internet were required to carry an instantly verifiable signature, documents without them could be prohibited. Once a document with a virus is detected, signature blocks could be set in Internet routers. Of course, the bad guys will cloak and clone legitimate addresses, but automated challenges could be set in place to block them.
Telltale signatures would be more easily identified in quick fashion, providing trace mechanisms for identifying perpetrators. Such a system would ideally be an extension of current DNS, controlling the backbone fabric over which all such traffic passes. Of course, safeguards would be needed to blunt hack attacks.
This is where law comes into the picture. With controls in place requiring registration by all and requiring all documents to carry valid signatures, free and unfettered access would be available only to those conducting business on the Net in appropriate fashion. If an e-mail marketer were to send out a campaign under the general instead of the appropriate marketing category with his signature, he would be violating the law and might even go to jail. If a porn purveyor were to publish content or send spam without the porn category on his signature, the consequences would be similar. Since filtration could easily be set for receivers to limit what they receive, nobody would be denied the right to publish or send whatever they desire. Thus, freedom of speech would not be an issue.
Such a scheme would be complex and impossible to fully describe here. However, it would be a significant step forward in the war to save the Internet for legitimate use.