1. A security system for interrogation of a communication transmitted over a communication network, the system comprising: a) a communication interface communicatively coupling the system to a communication network; b) a system data store comprising: i) a message data store capable of storing a communication; and ii) a queue data store capable of storing a plurality of index queues; and c) a system processor in communication with the communication interface and the system data store, wherein the system processor comprises one or more processing elements and wherein the system processor: i) receives a communication via the communication interface; ii) stores the received message in the message data store; iii) assigns a selected index to the stored communication; iv) executes a plurality of interrogation engines, wherein each of the interrogation engines has a test type and has an index queue in the queue data store associated with it, and wherein each of the interrogation engines: 1) monitors its associated index queue for a placed index; 2) retrieves the communication associated with the placed index from the message data store; 3) assesses the retrieved communication against a set of one or more criteria related to the interrogation engine's test type; and 4) outputs an assessment indicator indicating results of assessing the retrieved communication with respect to the set of one or more criteria; and v) places the selected index into the index queue associated with a first interrogation engine, wherein the first interrogation engine has a first test type; and vi) responsive to the assessment indicator output by the first interrogation engine, places the selected index into the index queue associated with a second interrogation engine, wherein the second interrogation engine has a second test type that differs from the first test type.