With all the efforts we go through to stop spam and to convince people not to respond to it, the fact that we still get so much proves that it must be working for somebody. Why does it work, and how can we try to stop it?
Even though only a tiny, tiny percentage of unsolicited commercial emails succeed in making sales, the miniscule cost of sending email means that it can still be profitable. As long as it's profitable, unscrupulous people are going to do it. Legal solutions and technical solutions can dent it, but without a complete overhaul of the email delivery system, the flow is unlikely to stop, or even slow significantly, unless the economics can be changed.
Possible approaches to changing the economics of spam include:
1) Make it more expensive to send email
2) Make it more expensive to get caught AND greatly increase the probability of getting caught
3) Convince virtually everyone to stop responding to spam
Which of these are good ideas? #3 would be great, but seems unlikely. #2? The first half can be done, but until the second is, it probably won't make much difference. Some are thus tempted to try #1--imposing a tax on every email. Hopefully we won't succumb to the temptation. That would punish everyone for the bad behavior of the few, and would both completely change the economics of legitimate businesses that depend on the low cost of sending large amounts of email to customers who've requested it, as well as reducing the number of free services available on the internet.
Slowing the flow of spam and mitigating the cost of spam that gets through will require a multi-pronged approach. Eventually, I think we're going to have to bite the bullet and replace the old infrastructure with a system designed form the start to make it easy to track messages back to their source so that the threat of legal action will provide a credible deterrent.