Amazon does allow you to build and manage your own mailing lists to promote their items so long as the visitors opt-in for your newsletter. Its a gray area, but yes, you can in fact generate income from it. Make sure you allow people to sign up on their own and add valuable content to keep them subscribed and you should do well. A good example would be offering weekly or monthly recipes newsletter and then linking to the ingredients and appliances used. This way the recipient can purchase the items they need for their new recipe and you generate income by helping people learn new recipes. It's a beautiful thing, lol. Happy Selling!, PuReWebDev