It's not a terribly common occurrence, but as the post archive grows and people use search facilities (both within the forum and search engines that have indexed the site) it happens that posts are resurrected months (sometimes years) after they were put to rest.

A lot of the time it is done by mistake, so what if the server-side script called by clicking a Reply button checks the last post date in the thread and inserts an intermediate "are you sure you want to dig up the past, this thread has been inactive for X months?" prompt if it is over a threshold.

Alternatively a check could be made on the user's rank to determine if they should be permitted to resurrect threads older than a certain amount, or a full-out block on replies to make the thread "read only".

Maybe people could be redirected or encouraged to start a new thread and link to the old one instead.

Yes, this idea came from an email generated by the board created by a reply to a 2-year old thread