Introducing Public E-Mail Gateways: An Effective Hardening Strategy Against Spam

Abstract

With the increasing popularity of the Internet, unsolicited electronic mail (spam) has become a major concern. It fills up user’s mailboxes, clogs mail relays, wastes postmaster time, and creates inconveniences for sites that have been used as a relay. This seems to be a growing problem, and without appropriate countermeasures, spam messages could eventually undermine the usability of e-mail. In this paper, we propose a cooperative spam-avoidance strategy based on the concept of restricting, at the network border and mail relay level, the mail sending function through properly authorized mail gateways registered as proper new Resource Records in the DNS System. If accepted and enforced by the largest number possible of network and mail administrators on the Internet, this strategy may result in a substantial reduction of the worldwide e-mail spam phenomenon.