By choosing to have emails sent to you on the main page "User Options" you can now opt in to have emails sent to you for
1. Comments made on posts only you submitted.
2. Comments made on any post on the site.
3. No emails at all (default)
Hope it is useful to you.
Remember, you can also get an email whenever there is any new submission to the site. Just visit your "User Options" that appears on the left menu section when you are logged in.