You can provide an input form on your web site to simply capture your visitor's email address. Those visitors who elect to add their address via the input form provide the foundation for a targeted mailing list. Then, you can keep them informed of new products, special prices, promotional offers, etc. Mailing lists developed in this fashion are a great way to keep your site visitors coming back.

In contrast, mass mailing lists (spam) are rarely effective and can actually lead to a bad image and a negative association with your web site. Unless your product is so compelling, it is best to avoid this tactic.