Bye Bye Spam and Phishing with DKIM?
Page 5 of the PEW Internet study reports that "...only 4% of email users admitted to action that keeps the spam industry viable, which is ordering a product or service from an unsolicited email. This number has always been low; it was 7% in 2003, 5% in 2004, and 6% in 2005."
These figures are interesting because there is often speculation about these numbers during conversations about the financial viability of being a spammer. The article suggests that these figures are "low" but they are much higher than the "back of the envelope" estimate of 1% that I usually see people use when guessing. It is going to be difficult to stop the spam problem when people keep buying things from spammers. Even if technical solutions like DKIM have some degree of success, such a high response rate to spam gives an obvious incentive to spammers to continue to find work-arounds.