Mailchimp is by far the largest provider for newsletters. Adding Mailchimp to your comment section is a no-brainer and is an easy way to get more subscribers through comments.
Mailchimp on the Front-end
With Mailchimp enabled in Comment Edit Lite, you'll see a checkbox just above the submit button.
Customizable Signup Text in the Comment Section
Enabling Mailchimp
Enable Mailchimp Toggle Switch
You'll find Mailchimp in the Integrations tab in Comment Edit Pro. If you're setting it up for the first time, you'll see an enable toggle switch.
Setting the Mailchimp API Key
Once Mailchimp is enabled, you can enter your Mailchimp API key.