There is a proposal for a proof of work system that does not require the sender to pay direct monetary fees and does not, significantly, slow down sending emails since it can be computed while the sender is writing the email.
I can't remember what it is called, but I hope somebody else can chime in with the name.
The smart thing about it is that you can use it as a filter in your baysian spam filtering systems. That way it can be implemented gradually, with no need to cut out everybody who doesn't yet use it.
I can't remember what it is called, but I hope somebody else can chime in with the name.
The smart thing about it is that you can use it as a filter in your baysian spam filtering systems. That way it can be implemented gradually, with no need to cut out everybody who doesn't yet use it.