Emails can be faked and/or altered, thus are not legal proof in court - unless they were taken from an impounded computer in some cases, or the server. If you repost alleged emails on the forum and someone thinks it damaged their character and/or business, then they may be able to execute a successful suit.
If you posted the generalities of the incident, and then sent detailed emails to those expressing a more detailed interest, I would think you would minimize the risk.