Very interesting new allegations in a lawsuit against Mark Zuckerberg, the founder (or at least a founder) of Facebook. (article here) Allegedly, new emails introduced show that Paul Ceglia may have been promised 50% ownership of Facebook. The emails being introduced as new evidence are from 2003. Could you defend or prove a claim from that many years ago? Not sure? Well, then my suggestion would be to avoid taking the approach that email can just be deleted quickly. In fact, quit thinking of email as simply email. IF you have not already done so, it is time to realize that your email may be a contract, a modification, or some other written legal instrument.
In the past, I worked with a few "consultants" purporting to provide "Best Practices" in this area and I used to argue vehemently against their approach. They liked to give simple answers to their clients and frequently guided them towards policies where they would delete/destroy all email after a set period of time, one year, 18 months, or 3 years. This was to avoid having to manage it according to a record retention schedule or, having to consider it as potential relevant information for a potential future lawsuit. These "consultants" really did not understand the law, but that did not stop them from offering "litigation readiness services."
Previous blog posts here (search Skupsky) discuss why it is not a "Best Practice" to simply consider all email, as email. It is arguably the main written correspondence method utilized today. Accordingly, any policy covering email usage and retention should be reviewed and set in light of your legal and business requirements and based on the content that might be contained in the email. This can be tricky. So, if you need help with this, get some. Even when not mandated by laws or regulations, like Sarbanes-Oxley, there are still rules that may apply to your emails.