Interesting article here on software that will render emails unreadable after a certain amount of time:
http://www.cfozone.com/index.php/BizTech/This-blog-will-self-destruct-in-five-seconds.html
It's normal for companies to have a set period for document retention, which makes practical sense. We can't be legally bound to be a bunch of pack rats, right? Oh and sure it can protect you legally, too. And that's where I wonder about this software: the argument for an email retention -or more accurately, reduction- policy is that storing emails forever can be very expensive. But this software only re-encrypts it and doesn't destroy it. So, you still have to store it, I presume. It seems that the sole purpose is legal protection. You have to wonder if that's going to fly with the courts.