Within the area of criminal and terrorist social network analysis, there is little research being done on analysing the communication behavior of criminal and terrorist groups. In this paper, we describe the development of a conceptual simulation model of the e-mail system, which is based on the use of personality trait dimensions to model the e-mail traffic behavior of e-mail users. This conceptual simulation model is being used as a first step for further development in simulating criminal and terrorist communication behavior. We also describe the development of an e-mail traffic analyser system, which uses a decision tree to search for interesting e-mail traffic behavioral patterns, and uses social network and time-series visualisation to provide the details of the interesting traffic patterns. We demonstrate that the personality trait based e-mail system model is useful as a tool for generating e-mail traffic behavioral patterns and that decision trees are useful for finding inter...