1. A method for reputation-based threat protection, the method comprising: maintaining one or more dictionaries for identifying the sensitive data in memory, wherein the sensitive data is defined by policies of an identified organization; intercepting an e-mail message from a sender in the organization and addressed to a destination outside of the organization, wherein the e-mail message is intercepted prior to leaving a communication network of the organization; executing instructions stored in memory, wherein execution of the instructions by a processor: determines that the intercepted e-mail message includes sensitive data by reference to the one or more dictionaries stored in memory for identifying the sensitive data, and identifies the e-mail message is a threat based on the determination that the e-mail message includes sensitive data; and notifying the sender that the e-mail message was determined to be a threat.