I’ve given away 10000s of copies of my books to new readers in return for them joining my mailing list. It’s well worth the effort, but it was getting to the point where helping them to sideload to their devices was becoming a bit of a time suck. I’ve been looking for something like BookFunnel for ages and, after a little bit of healthy skepticism, I’ve been blown away by how good it is. It’s the best tool I discovered last year, by far. I’ve introduced several hundred of my students to it, too, and they have been uniformly lavish in their praise. VERY highly recommended if you want to build your list and maintain your sanity.