Dialog in e-Mail Traffic

Connectivity and topology are known to yield information about networks, whose origin is self-organized, but the impact of {\it temporal dynamics} in a network is still mostly unexplored. Using an information theoretic approach to e-mail exchange, we show that an e-mail network allows for a separation of static and dynamic structures within it. The static structures are related to organizational units such as departments. The temporally linked structures turn out to be more goal-oriented, functional units such as committees and user groups.