You will probably find that MySQL is bound to the loopback address and hence unable to access it from another server. There are a lot of metrics help in the MySQL database especially around MTA and Amavis statistics. If you log onto your ZCS server and look at
and then describe some of the tables. If you open up SSL to your Hyperion server you should be able to generate some queries for these. You could then monitor whether your defered queue etc is building up.
su - zimbra