1. Email Statistics Report;The Radicati Group,2016
2. Commtouch Q1 Internet Threats Trend Report Highlights Strong Increase in Spam and Dangerous Email;Commtouch,2013
3. Spam in Q1 2013;Gudkova,2013
4. Exploiting network structure for proactive spam mitigation.;Venkataraman,2007
5. The case for spam-aware high performance mail server architecture;Pathak,2009