Eliminating the Volume of Spam E-Mails Using a Hashcash-Based Solution

Abstract

Spam can be defined as unsolicited e- mail, often of a commercial nature, sent indiscriminately to multiple mailing lists, individuals, or newsgroups. Spoofing (Templeton and Levitt, 2003) is a technique often used by spammers to make them harder to trace. Trojan viruses embedded in e-mail messages also employ spoofing techniques to ensure the source of the message is more difficult to locate (Ishibashi et al., 2003). Spam filters and virus scanners can eliminate only a certain amount of spam and also risk catching legitimate e-mails. As the SoBig virus has demonstrated, virus scanners themselves actually add to the e-mail traffic, through notification and bounceback messages. Simple Mail Transfer Protocol (SMTP) is flawed in that it allows these e-mail headers to be faked and does not allow for the sender to be authenticated as the real sender of the message. If this problem can be solved, it will result in a reduction in spam e-mail messages and more security for existing e-mails, and it will allow e-mail viruses to be tracked down and stopped more effectively (Schwartz and Garfinkel, 1998). This approach is known as “trusted e-mail.”