Circle ID has an interesting piece entitled Internet Governance: An Antispam Perspective by Meng Wong, who is known for his work on the email authentication mechanism SPF*:
I believe that we must move to a default-deny model for email to solve
phishing; at the same time we must preserve the openness that made email the
killer app in the first place. The tension between these poles creates a
tremendous opportunity for innovation and social good if we get things right,
and for shattering failure if we get things wrong.
* SPF is derived from original concept work by Paul Vixie which is now also the core of Microsoft's
Sender ID.