I have just recently started to respond to comments, so sorry I didn't in the past! I've been emailing the person directly from the notification email I receive - as long as there is an email to respond to.
On my comment section, I have enabled the comments to show reply, but wouldn't the person who wrote the original comment need to have clicked "Subscribe by email" to see it? Does any of that make sense?
I know I don't always subscribe after leaving a comment on a blog, but am wondering if I should?
Example - Here are two comments on my post "Our 2nd Jingle Bell Walk for Arthritis"
What a great family/friend walk for an important cause. You have a great group and the pic of your Mom and Dad is so sweet.
Hugs!