Michael G. Kaplan writes: "Distinguishing between spam and legitimate email is difficult because it is frequently not possible to identify the computers from which an email originated. Email forwarding and the use of dynamic IP addresses can make it impossible to verify an originating mail server, while the personal computer that first sent the email is effectively never identified. A novel method offers a practical solution to this problem by authenticating nearly every email server and personal computer in the world. An introductory explanation of this method is the best place for non-experts in the field of email authentication to start. The core process of this method will also finally make it possible to do away with CAPTCHA."