Data Loss Prevention is a term used to define and enforce data classification and uses robust encryption and security. Vendors like Vontu , Reconnex and Titus Labs, all produce software that is classified as data mining technologies and gives the user the function/ability to include the security option which they can define the level that should be applied.
These types of software scans email and their attachments along the files users already have and create giving the users a sign that the said files are in need of protection. They then assign the level/s of protection that are assigned and the file is encrypted with a key. Only authorized clients and users with the right access levels get the key and thus access to the said information eliminating the reliance on the traditional walls for protection.