I have a small but growing mailing list of just under 500 readers. (everydayauthor.com)
You also have the option of requiring readers to share their email addresses in order to download the ebooks, so it can be a way to start growing a mailing list. (marketingsff.com)
We're still trying to work out the best way but we've found that it's certainly something that can have a big impact on growing our mailing list. (blog.reedsy.com)