Actually, I’ll take it a step further: Don’t mass-email people if you haven’t asked them to opt in to your mass email list. I’ve been added to multiple mailing lists without signing up. And most of them also have no easy option to unsubscribe.
(I’d be less bothered by this if most of the mass emails weren’t asking me to pre-order a book I already ordered, but that’s beside the point.)
The reader update module on the site is a wonderful tool that bakes in the reader’s right to opt in or out. People who follow your book have told you it’s totally cool to send them updates through that. Anything beyond that, you need to ask.
