Here’s a great article by Mich Kabay that describes tips for defining email retention policies.

Here’s an excerpt:

• Define, enforce and update formal retention policies that stipulate how long to keep archives of which types of data. Ensure that your legal counsel is deeply involved in setting these policies.
• Access to archived records should be completed within, at most, 48 hours to avoid possible fines.
• Deleting e-mail and other records that show evidence of wrongdoing may lead to worse legal and public-relations consequences than coming clean.
• Unscheduled deletion of e-mail may destroy exculpatory evidence or lead to a tacit presumption of guilt.

Great info for anyone developing their own e-mail retention policy. Check it out!