It’s common on CC to find a thread that’s been dormant for years resurrected by a new post. That’s OK if the most recent poster felt that the discussion was valuable enough to bring back up. But in many cases, it appears that the recent poster may have come across the thread while doing a search and not realized how old is it (such as when s/he gives college selection advice to a poster who was asking about various colleges several years before).
Would it be of value to have a message pop up whenever a poster attempts to respond to a thread in which the last post was over a year earlier? The message could point out the age of the thread and ask whether the new poster genuinely wishes to communicate to people who dropped the discussion topic so long ago, or whether they might prefer to initiate a new thread that could more precisely address the topic that they wish to discuss.