A migrated question only lives on one site. Migrating locks the question on the original site and creates it on the target site. When a migrated question is closed (for any reason other than duplicate) on the receiving side, the migration is marked as rejected: the question again belongs to the sending site and is unlocked there (where it remains closed, since it's as off-topic as it was in the first place). When a migration is rejected, it is locked on the target site that rejected it, to avoid having two diverging copies of the same question.
While this question is marginally on-topic on its original site Unix & Linux, inasmuch as it concerns software that would run on some Unix variant, the Unix aspect is marginal, so this question is better suited to Software Recommendations. Furthermore the U&L question has now been deleted (stubs of migrated questions are deleted automatically after a month). So we should work on this question here on SR.
Undo has unlocked the question, it can now be edited. I've cleared the migration history, to avoid any further trouble. (Both actions are moderator-only actions.)
The question is still severely lacking in information that would make it answerable. There are a great many forum implementations out there, and most include features to combat trolling. In order to be viable, the question needs to be edited to include a reasonable set of concrete requirements, such as:
- Protocols (e.g. web-based, email, NNTP, …)
- Message management (threads, groups, …)
- Privilege management (who gets to do which moderation activities)
- Expected moderation features (deletion or edition of messages, account suspension or banning, etc.)
Only software recommendations are on-topic here, books and papers are not. Questions about the human side (how to effectively use such software) — the actual questions on the topic, not questions asking where to find answers — are best asked on Moderators Stack Exchange.