Having comments is great. However, old posts tend to attract annoying spam messages, so once posts are more than about a month old, and no longer appear on the blog’s main page, I usually close them to new comments.
But a problem with doing this is that once in a while somebody leaves an extraordinary comment on an old post. Some of these comments come months after the original post and are from people who have some connection to the subject of the post.
See, for example, here, and the last comment here. And check out the last comment on this old post about the Mongolian army, which was made just last night by a Mongolian army reservist who lives in the U.S. These comments got through only because in the first two cases I was not yet in the habit of closing comments on old posts, and in the case of the Mongolian post I hadn’t yet gotten around to closing them for the latest batch. (I have left the Mongolian post open to comments in case anyone wants to respond to Amar.)
So does anyone know of a better way to handle comments? I hesitate to use the “copy this number” anti-spambot system that other blogs, e.g., Samizdata, use (for an example, see here and scroll down to the “Post a comment” section), because it’s burdensome for users. I thought of closing comments, but also posting a conspicuous message suggesting that commenters email us if a thread is closed, but that’s burdensome too. Another alternative is to leave comments open longer, but also to hack Movable Type so that the editing window displays more than the five most recent comments (Steve does something like this). In that case we would still get spam but it would be easier to find and remove.
Any other ideas?