Each and every WordPress.com follower controls their own subscription settings. They can choose to receive notifications only in the WPcom Reader, or have an immediate email notice of new posts or a daily or weekly digest of new posts. See here: http://en.support.wordpress.com/following/#change-your-email-settings
People who are not WordPress.com members can only receive email notifications and can adjust their settings by clicking on the Manage link that appears in the email confirmation they received when signing up on your site.
Technically you can test your site yourself by signing out and following your blog with a different email address than the one associated with your WPcom account. You will, however, have to publish a new post in order to complete the test.