Overview

Many email users understand the value of utilizing more than one address as a best practice for controlling spam. This is clear in the common practice of disclosing a temporary email address from a free email service in order to protect one's primary address from accumulating spam.

Yet a corollary to this practice is not so clearly recognized: it is extremely difficult to separate desired messages from spam — with true precision — when all messages, good and bad, are sent to a single address. Between false positives, challenge/responses and other side effects, no current spam prevention scheme delivers a pristine inbox without introducing negatives. The use of supplemental addresses solves this problem.

The efficacy of supplemental addresses is supported by a universal truth in email communications:

Legitimate contacts never knowingly share your email address with spammers, and spammers only share your address with other spammers, never with legitimate contacts.

Imagine software that transparently changes the email paradigm from having all email arrive at a single address, to one where inbound mail arrives under two or more addresses. Messages from different sources arrive via separate “conduits” that can be individually controlled and transparently managed by the application. Messages from legitimate correspondents sharing a supplemental address can be spared examination by whatever anti-spam security solution is deployed, and never suffer false positives or trigger challenges. Conversely, addresses disclosed on the Web can be filtered, restricted or disabled altogether without any impact on mail to any other supplemental address.

The net result of using supplemental addresses is astonishingly beneficial. For example, if the false positive rate of a content filter is 1% on average, but 90% of messages from legitimate correspondents arrive on unrestricted supplemental addresses, the rate of false positives will be reduced by an order of magnitude. Additionally, by associating correspondents with different addresses, one can detect address sharing and phishing exploits, and track the effectiveness of email marketing campaigns.

Furthermore, when the use of supplemental addresses is combined with whitelisting, the rate of challenge is greatly reduced. The rate continues to decline the longer this system is used, because an ever growing percentage of mail takes place on unrestricted supplemental addresses that do not trigger challenges when shared.

Technology now exists to create supplemental addresses “on the fly” for disclosing an address on the Web or over the phone. If one desires, the supplemental address model can also be fluidly perpetuated in a fully automatic fashion for all new correspondents.

By using supplemental addresses for email communication, organizations can stop spam, eliminate false-positives, and protect against DoS and DHA, while empowering users and administrators to track sharing events and eliminate on-going maintenance. Two addresses are better than one, three are better than two, and users can now extend this advantage as far as they wish.