I don't know about you, but I can count on one hand the number of times I've voluntarily signed up to a mailing list without being bribed or coerced and then spammed. So I'm not doing that. All this mailing list does is notify you by email when I release a new book. I've tested it myself by signing up to it with dummy email addresses, and they've never been spammed.
(If you do want newsletter-type content, you can find that at my blog, which I update at least monthly.)
The above Books2Read mailing list is run by my bookstore aggregator, Draft2Digital. If you prefer to know when you can buy new books directly, there is a similar Follow option at the bottom of my Payhip storefront. However, I haven't tested that list yet.