Automatic and Reliable Elimination of E-mail Loops Based on Statistical Analysis

One of the major threats to the E-mail service are message loops, mail messages which endlessly circulate between a number of E-mail relays and severely deteriorate or even interrupt the messaging service. Although the standards ruling E-mail communications include mechanisms to prevent message loops, these mechanisms are often unimplemented and, if they are, can fail to work reliably under certain circumstances. This paper describes a novel approach to the automatic and reliable elimination of looping messages. Statistical properties of the message traffic are analyzed to detect messages that might be looping. Such messages are earmarked, and if they are observed to actually be looping, they are eliminated. This method has been implemented and successfully applied in the multi-protocol E-mail environment of the University of Geneva.