What is the difference between the "Customers" list and the "Interested Readers" list?

On the Overview page for your book, in the "Community" section, you can find links to a "Customers" list and an "Interested Readers" list:

he "Interested Readers" is a list of people who sign up before you publish your book for the first time; they will be notified via email when you publish the first version of your book.

The "Customers" list is a list of people who actually buy your book after you have published it, and who have also opted in to share their email address with you.

Why don't I get all the reader email addresses? Is it possible to see the details of the readers who purchase one's book?

I’m brand new to authoring on Leanpub, but I’d like to take a “lean” approach and gauge interest in books, interact with interested readers early (before some content is written) and others. What’s a typical flow for this type of development?

I want to email my readers to ask for feedback. How can I do this?

I'm a Leanpub author. Can readers of my book or course share their email address with me? If they do, where can I find a list of shared email addresses?

I want to stop selling my book on Leanpub, but it is not finished. What should I do about people who have bought my book on Leanpub?