It seems here is going on quite some necroposting recently. I came across a thread where @LaneFox and @FMark92 started to suggest how one could prevent that, see here and here. I have a similar idea: Use the date when an user joined the forum to either allow or disallow to post in an old thread. If the "joined date - 14 days" is older than "last activity in forum thread", then the person is allowed to resurrect that thread. This would prevent new users from resurrecting old threads, while users who already joined the forum when the discussion was active, can still contribute. The "14 days" is to allow that new users can still participate in relatively new discussions, that they found via google for example and just created a new account to ask an additional question in this thread.