The propagation of messages among a group of people, which forms opportunistic Disruption Tolerant Networking (DTN), can be modeled as dynamic graph with links joining every two nodes up and down at a stationary speed. As people in DTN might have different probabilities of sending messages to each other, they should be divided into distinct groups with different link generate speed λ and link perish speed µ. In this letter, we focus on the two-group case, and apply Edge-Markovian Dynamic Graphs to present an analysis framework to evaluate the average delay for the information dissemination in DTN. We also give extensive simulation and numerical results revealing the influence of various parameters.