Unsolicited commercial electronic mail, commonly referred to as spam, has continued to wreak havoc with electronic communication. Such email consumes significant bandwidth, users' productivity, and disk space. Several solutions have been proposed to eliminate spam in the last few years. We broaden the definition of spam as any email unwanted by the intended recipient. We propose a novel scalable scheme that aims to add monetary cost to senders of such unwanted mail while allowing legitimate mail to be exchanged at no cost to users and in the same manner as today. Our scheme is entirely complementary to the large number of receiver-based filtering ideas in use today. We describe our scheme, describe how it can be integrated into the existing Internet email infrastructure, and discuss our prototype implementation. Our scheme will neither outlaw spam, nor make it obsolete; however it will add monetary cost only to spammers thereby increasing the potential of lowering the frequency and amount of spam.
Zalachander Krishnamurthy has published in various conferences including IMC, SIGCOMM, WWW, Infocom, Usenix, USITS, etc. He has co-authored a Proposed Standard on adding a delta mechanism to HTTP/1.1. He has co-written and edited a book on UNIX, and was series editor for 8 volumes in the 'Trends in Software' series of books. With Jennifer Rexford, he co-authored 'Web Protocols and Practice: HTTP/1.1, Networking Protocols, Caching, and Traffic Measurement' (672 pp, Addison-Wesley). Portuguese, Japanese, and Russian translations of the book are available. A special issue of the Wiley Journal 'Software, Practice and Experience' on Web Technologies guest edited by Bala appeared in Feb 2004. He is on the editorial board of ACM TOIT and SIGCOMM CCR, and on the Steering Committee of the popular Internet Measurement Conference (SIGCOMM/Usenix) that he helped start three years ago. He has more than a dozen patents, published nearly sixty papers, and has given invited lectures in over thirty countries. Bala is homepageless but many of his papers can be found at http://www.research.att.com/~bala/papers