One preferred embodiment of the present invention provides a system and method for checking the performance of sub-systems in an inter-messaging network of voice mail systems. This preferred embodiment includes a network diagnostic device that connects to the inter-messaging network and requests a test data file to be retrieved from all the voice mail sub-systems in the inter-messaging network. The requests for the test data file are generated without user interaction. Accordingly, the performance of the inter-messaging network in its entirety, as represented by the results of the request attempts, is assessed according to a defined level of performance, such as a preferred time limit. Other systems and methods are also provided.