One of the evil tricks that spammers get up to is to go into the older posts of your blog and spam the comments. In many cases, closing comments on these old posts will stop spammers from attacking your blog. Blog posts, like internet forum posts, have a life span. When you write a new post, it gets its most comments when you initially publish it. As time goes by, the legitimate comments just stop coming. While sometimes, you may written about a topic that just keeps the conversation going and going for months, chances are most of your posts have reached their conversational life span.
The spammers know this, so they dig back into your archives, leave spammy comments and hope you won’t notice. There is a setting in your blog’s dashboard that allows you to close the comments on older posts. You set in days, so you can decide how old you want posts to get before your blog automatically closes the comments form. You’ll find the place to do this in your dashboard under Settings -> Discussion. If you are getting hit hard with spammers on your older posts, turn this feature on and it will automatically reduce the number of places spammers can target you. Check out the setting in the image below, click to enlarge it to get a better view.
Don’t worry, closing the comments does not hide existing comments, it just closes the ability to add new ones. The great conversations that your readers had about your post will still be displayed. While when new, legitimate readers stumble upon your blog through one of your old blog posts they won’t be able to post comments, it is generally bad form to revive a dead topic. Besides, you should be wowing them with great, fresh content anyhow on your home page.