Abstract: This article analyzed the email communication patterns of users reflected in a national university’s email network. It is shown that the two existed models, prioritybased queuing model and the cascading nonhomogeneous Poisson process model, both fail to describe properly the dynamic mechanism in the email network. The hypothesis in the prioritybased queuing model that users share a universal behavior pattern is unreasonable; besides the cascading nonhomogeneous Poisson process cannot embody the unexpected cessation or dynamic evolution in individual activities. Therefore, the clusteringanalysisbased segmented cascading nonhomogeneous Poisson process model is promoted which can produce better predictions.