1. A messaging system comprising: a communication server comprising computer hardware and in communication with a plurality of client computing devices comprising computer hardware, the communication server configured to initiate and administer messaging sessions between two or more of the client computing devices; a graphical user interface configured to provide input functionality allowing a user to specify criteria for identifying messages of interest, wherein the identification takes place subsequent to delivery of the messages of interest and prior to storage of those messages in a storage destination specified in a compliance policy; one or more memory devices storing the compliance policy specifying at least the storage destination and the criteria entered via the graphical user interface; and a computing device executing a compliance agent and in communication with the plurality of clients and the one or more memory devices, the compliance agent configured to: access the compliance policy; monitor the messaging sessions; for a first monitored message including an audio data portion, convert the audio data portion to converted text; subsequent to delivery of the first monitored message and prior to storage of the first monitored message in the storage destination specified in the compliance policy, based at least on the criteria specified in the compliance policy for identifying messages of interest, process the converted text to identify the first monitored message as a first identified message of a plurality of messages of interest within the messaging sessions, wherein the identified messages of interest have files associated therewith of at least a first type and a second type, where the files of the second type are generated with a different software application than the files of the first type; direct storage of identified messages to the storage destination specified in the compliance policy; and convert those of the identified files that are not in the common file format type specified in the compliance policy to the common file format type.