Chapter 15 Unified Threat Management for FortiOS 5.0 : Security Profiles overview : Content inspection and filtering : DLP : DLP recommendations
  
DLP recommendations
Rules related to HTTP posts can be created, but if the requirement is to block all HTTP posts, a better solution is to use application control or the HTTP POST Action option in the web filter profile.
While DLP can detect sensitive data, it is more efficient to block unnecessary communication channels than to use DLP to examine it. If you don’t use instant messaging or peer-to-peer communication in your organization, for example, use application control to block them entirely.