Subscribe to INDIVIDUAL Post needed

Good day,

I am trying to find a plugin that will allow subscription to individual posts, so that I can have a manageable list of contacts per post. First/Last Name, and Email are preferable options.

The ultimate goal is a favorite icon, such as a heart, etc, that when you click it, asks for your name and email and adds you to a list.

It would be great to have that list exist in WordPress, rather than send it to MailChimp which would require a subscription once the subscriber base grows.

I can always build mailchimp lists from my master subscriber list.

Thanks.