[In Omnibus]

There is no inherent right to privacy on a message board. Ethics are a matter of opinion. The only legal issue with reading private messages is in that your right to the information ends with breaking either your own privacy policy or other existing laws, such as the dissemination of personally identifying information publicly.

If a forum administrator , for example, obtains a member's real name, address, telephone number, social security number, employer, credit card information, etc. and uses it in a manner clearly intended to cause or likely to cause legal damages that's an issue.

If a forum administrator uses the information purely for his or her own internal use to determine if members are spamming, or otherwise disrupting the community there is no issue. It's done all the time. There's not even an ethics debate in such cases.