Barnako, Frank. Evidence Piles Up in E-mail. Investors.com. Oct. 19, 2004.

Good article on the need for discovery of e-mail .... keep in mind the 4 main places you need to be able to discover for compliance reasons ... in your Exchange servers, in your backups, in your archives and in PSTs throughout your environment (unless you can manage PSTs/restrict them/archive them/etc.).