Where are these blog hits coming from if I only have one email subscriber?

I guess I’m sort of blog stupid…

I have a blog on WordPress. I have one email subscriber, but every day that I post, I always have a boost of visitors as compared to a day when I don’t post anything. If I have one person subscribing via email, is it just a coincidence that I get more hits on post days? Or is there some other way someone can be notified that I’ve posted something other than email?