Encouraging interactions between authors and readers is important to us at Leanpub. It is a key part of the Lean Publishing process. We do offer a number of communication features.
Now, obviously we are not going to provide authors with private contact information that belongs to their readers, like their readers' email address, unless they choose to share it with the author.
First, you can check to see if anyone has opted in to share their email address with you, by going here:
...making sure to replace YOUR_BOOK with your book's unique web address.
You are permitted to contact people using the email addresses provided there, just be sure to explain everything clearly and politely.
Second, we highly recommend you publish a new version of your book on Leanpub, with a new section called "A Message to My Readers" at the beginning of the book, that explains the fact that you would like to be able to contact your readers. In that new section, we recommend you add your email address, so anyone who wants to get a full copy of the book eventually, can contact you and give you their email address.
Third, when you publish the new version of your book with a significant amount of new content, you may use our feature to notify your readers when you publish the new version of the book. Only readers who have opted in to this feature will get the email, but most Leanpub readers do opt in to this feature, particularly readers of unfinished books, who are expecting updates. DO NOT use this feature to spam readers with product offers and announcements.
Fourth, we recommend you update the About the Book details of your book with a similar section called "A Message to My Readers", where you explain that if they buy your book, they will see a section at the beginning of the book, with your contact information.
You can edit About the Book section of your book here:
Finally, we recommend you enable the Forum for your book here:
Good luck! We hope you have fun interacting with readers, and it helps you grow your audience, and help sell more copies of your books.