A violation of Massachusetts' public records laws by Boston mayor's top aide provides a perfect example of why companies need data retention policies. There are several options for addressing the e-mail portion of the risk.
Manage Insider Data Risk [1] | Source: The Big Fat Finance Blog [2].
Links:
[1] http://bigfatfinanceblog.com/2009/09/21/manage-insider-data-risk/
[2] http://bigfatfinanceblog.com/