Comments should send e-mail to other comment authors

As a reader of other people’s blogs, I like to drop by sometimes, but not too often. When I see something interesting, I may post a comment. I don’t go back to check if someone replied to me, but would like to know anyway. Therefore I suggest e-mail notifications to comment authors: add a checkbox when posting a comment to “receive an e-mail when a new comment is posted”. That should of course only be for comments to that article, not for the whole blog. And it should be a checkbox, so people can also not do it, if they don’t like it.