Extended Comment Options allows you to close or open comments on batches of posts. You can schedule this automatically, too.
WordPress allows you to close comments or pings on individual posts, but if you want to close comments and/or pings on more than 10 posts, you're in for a long ride! Extended Comment Options allows you to close comments or pings (or both) on all your posts at once, if you want. You can also choose batches of posts based on criteria you specify:
The last two options can be set to update automatically. So you can close comments on the last 5 posts, and keep them closed as you make new posts. Or you can set it so that comments are closed on a post after the 10th one has been left.
Extended Comment Options also allows you to exclude certain posts. So, for example, if you want to close posts older than 5 days, but you have a popular post that draw a lot of comments, you can opt to leave it alone. You can choose as many posts as you'd like.
This plugin was originally developed and maintained by Mark Kenny. FullThrottle Development took over with version 2.6 Mark Kenny: http://beingmrkenny.co.uk/