Jetpack includes a subscriptions module which allows your readers to easily subscribe to your blog in order to receive updates by email on the latest comments and posts. This powerful feature helps to encourage more of your visitors to become regular readers, and it is one of the most effective solutions for setting up email subscriptions for a typical blog. Instead of using your own hosting package to handle the potentially large volume of emails you’ll be sending out, Jetpack uses the servers at WordPress.com, and best of all, it doesn’t cost anything either. The Subscriptions service should be activated by default once you have set up Jetpack, but you can turn it on and off from the Jetpack > Settings page as with any other module belonging to the plugin.
By default, email subscriptions will already be already be turned on, and your visitors will see checkboxes when they leave a comment on one of your posts or pages. When a reader leaves a comment, they will be able to choose up to two options including email notifications when someone posts a follow-up comment or when you publish a new post. Additionally, you can place the Blog Subscriptions widget in any desired widget area or add the option to subscribe anywhere else on your website by using a small piece of code.