Fighting spam using social GateKeepers

Abstract

We introduce LENS (LEveraging social Networking and trust to prevent Spam transmission), a novel spam protection system which leverages the recipient’s social network to allow correspondence within the social network to directly pass to the mailbox of the recipient. To enable new senders to send emails, legitimate and authentic users, called GateKeepers (GKs), are selected from outside the recipient’s social circle and within predefined social distances. Our evaluations show that LENS provides each recipient reliable email delivery from a large fraction (up to 55% of entire userbase) of the social network; it is also effective and lightweight in accepting all the legitimate inbound emails in the real email traces. LENS imposes zero overhead for the common case of frequent and familiar senders, and remains lightweight for the general case. Our prototype implementation of LENS in Postfix/MailAvenger shows that LENS consumes up to 75% less CPU and 9% less memory as traditional solutions like SpamAssassin.