The protection of sensitive data leaving the boundary of your organization is very important. For that there are encryption rules that can be matched with regular expressions in FOPE to ensure that the email data leaving your organization is protected in the manner you deem acceptable. This is a great way to ensure that precautions are taken in the management of sensitive materials and datum. I don't think I have used the word datum in about 10 years. It was overdue for sure. Here is a great video I found on TechNet under the Forefront Tech Center from Technical Writer Micah LaNasa explaining the Encryption Policy rules....enjoy!