Before to send an e-mail, the sender should get a free Уpostage stampФ on a page, corresponding to the destination e-mail. The Уpostage stampФ is a graphical image with a code or another kind of CAPTCHA. The code could be recognized with a human only, not with an OCR system. Sender adds this code to the e-mail and sends one. Recipient checks the code validity to define either is the e-mail spam or is not.