Restraining transmission of unsolicited bulk e-mail

Filtering large amounts of unsolicited bulk e-mail, also known as spam, is expensive. Either because of the time spent on manual deletion or complex analysis by algorithms putting heavy load on e-mail servers. Due to exponential growth of the volume of spam campaigns, Internet Service Providers (ISP’s) are increasingly forced to use rigorous rejection policies to prevent their filter servers from being overloaded. Concurrently, legitimate e-mail servers end up in blacklists due to compromised end-users. This endangers the reliability of e-mail communication and the process of automatically filtering spam. Transmitting spam is currently easy, cheap and mostly anonymous. Restraining spam transmissions at the source network could put a halt to this; furthermore, it is less complicated and cheaper than filtering at the destination network, because of lower volumes and easier detection. This paper proposes a novel architecture designed to restrain spam transmissions at the source network. Experimentation suggests 75% to 100% of all spam campaigns could be restrained relatively easy and cheap if ISP’s and hosting providers would enforce simple restrictions and checks on the outgoing e-mail of their end-users.