Spam yields only a tiny fraction of a percent. Internet entrepreneurs who use personalized messages always get better results. Alternately, you can create your own opt-in list. The most obvious place to start is with your existing customers. Offer them a discount on future purchases in exchange for agreeing to receive your promotional messages. Also, create something of value to draw in new customers. For example, suppose you sell rare coins on the Internet.
Create a well-written weekly newsletter that coin collectors will enjoy reading. Offer free subscriptions for anyone who agrees to receive your promotional email list email marketing messages. Don't stop there, though. Consider every point where there is customer interaction as an opportunity to sign up a new member to your list. Provide an opportunity to opt-in with customer orders. If you have a brick-and-mortar store, ask for email addresses at the point of checkout.
Growing your own opt-in email list will take longer, but your results will be excellent. Some marketers optimize their results by using both techniques. Creating your own opt-in list does require a bit of technology. If you have a very small list, you can start out simply by adding each subsequent subscriber to the "BCC" list on your email client, but this will get cumbersome as your list grows. You will want to eventually invest in an email list management program.