Maybe you should have asked him if it is ok if you post his...

Maybe you should have asked him if it is ok if you post his email to a public bulletin board. I think you will find he was a little more pi$$ed that you abused some kind of personal trust that exists between two people on an email. Imagine if you said something about your boss and a friend forwarded the email on to everyone else. Not the same situation sure, but it is the same abuse of trust without first seeking consent.

SF