Combining SMTP and HTTP tar Pits to Proactively Reduce Spam

Unsolicited commercial emails (UCE, spam) are currently being fought using reactive methods, filtering being the most common. Reacting means to be always one step behind. So the focus on fighting spam should be on prevention. Current proposals focus on fixing SMTP's lack of authentication, but introduce two major problems: First of all current attempts break existing functionality and, second, it seems to be hardly possible to enforce a world wide change of SMTP. Therefore other preventive measures should be implemented. The most promising approach is to prevent spammers from collecting email addresses. Several proposals show ways to obfuscate addresses on web pages, another proposal was to create HTTP-tar pits in order to catch harvesters. Our tests with real world harvesters showed room to improve those tar pits by combining them with SMTP tar pits. We report on the success of our experiments with this combination.