I'm planning to migrate to a multiple mailbox Zimbra system. I've setup a Zimbra proxy in preparation. What I want to do, before I swing all the accounts to the proxy, is to check the difference of performance of the proxy vs the mailbox server.

I used a tool called imaptest to try and get a feel for the performance of the mailbox server vs the proxy server with limited success. Does anyone have any suggestions for benchmarking or load testing Zimbra?