Empirical analysis of Denial of Service attack against SMTP servers

In this paper we show that the performance of the generic SMTP servers are more limited than we previously thought. We implemented a environment to test SMTP server performance focusing on denial of service (DoS) attacks. Our measurements show that a standard SMTP server can be easily overloaded by sending simple email messages and the overload can occur without consuming all network bandwidth. Our measurements also show that the usage of content filtering applications can harm the performance so much that the server become even more vulnerable to DoS attacks. In the paper we describe the problems of performance measurements in SMTP environment and we also give a detailed background about the performed measurements.