Competing with Spams More Fiercely: An Empirical Study on the Effectiveness of Anti-Spam Legislation

Spam mail still accounts for more than 80% of the total email traffic. More recently, it has played a role as a potential propagator of vicious attacks such as viruses, phishing, and malware. Although anti-spam legislation has already been established in many countries, it appears to be ineffective. In this context, the anti-spam policy regime in South Korea was radically changed in November 2014, which provides a natural experimental setting to investigate the effect of the policy. The policy change includes a set of the substantially enhanced regulations, such as a transition from an “opt-out�? to an “opt-in�? approach, informed consent requirements periodically, and an increase of maximum penalty. This paper empirically tests whether the policy effectively reduced the intentions of spammers in South Korea. For empirical work, we use a unique and large-scale dataset of 5.6 billion spam messages originating from over 200 countries during a twenty-month period. Our main findings suggest that this policy change significantly decreased the spam volume in South Korea, compared to those originating from other countries. We conduct an additional economic analysis and find that the expected benefits for users are up to 150 million USD in the country. Despite the importance of preventing spams, there have surprisingly been few studies on the topic from the policy perspective in the information systems field. This paper contributes to the literature by highlighting the importance of the properly designed policy to reduce unsolicited messages on the Internet.