Comments:

I fail to see why those trying to end/reduce spam continue to have problems with identifying spammers and enforcing controls. The whole approach and problems stem from the need to identify and act on the sender, who is unknown, offshore, etc etc. Every spam email has as it's purpose selling a product or service, and provides through links eventually a means to buy the product or service. So, simply control/penalize the beneficiary of the spam, the product or service provider,who is identified by where to send your credit card payment. and who is the reason the spam exists, and is the direct beneficiary of it's use. Charge, control, penalize these beneficiaries of the spam, and leave it up to them to control the spammers acting as their advertising agents. When the beneficiaries start to hurt, and quit signing on with spammers because it doesn't pay, the spammers will dry up.