it is possible for Ispy to send a large amount of mail. ISpy sends server and mail probes and stores the statistics. (configured through DDM). ISpy (runjava) will run automatically once probes are enabled. If you want to really evaluate the mail usage, select a few users and report on their mail, then you can see if it is working as you expect. There is not a tool to read this report, as it is pretty self explanatory.