On October 11, 2006, CNN published an article in their online Technology Briefingroom section: Shortcuts: Keeping your inbox in shape
Regarding the keeping or archiving of e-mail, it contained various recommendations such as "Delete Ruthlessly".
Some corporations such as jetBlue (anyone know of others?) have used this article and / or referred to it in the development of their corporate e-mail retention policies. Some of these policies mandate that, except in special circumstances, all corporate e-mail must be forcefully destroyed after 90 days. In some cases the company software is configured in an attempt to make it impossible for people to even keep personal archives of such 'corporate' email.