Its makes you happy when someone leaves a comment on your blog, but see that most of comments are left for help or asking a question, so they would require a immediate answer to their question. In the meanwhile you are not aware of when was the comment left, you can get notified to your mail by simply enabling this little tips in your Google free hosted blogger blog.

By default blogger theme doesn’t comment with automatic email notifications for comments moderation, you need set the settings accordingly to receive such notifications.

Navigate to Comments under Settings in the respective blogger blog.
Now scroll down and look for Comment Moderation.

In Comment Notifications at the bottom of it select provide your email address to get notified of the comments and click on settings. You can enter upto 10 email addresses and email would be sent to all of them when some one leaves a comment on your blog.