Give people the option to sign up before you give them a free offer
One way to purify your double optin leads list of people who respond to a free offer on your site is to require that they optin before they receive your free product. Most people will enter their email and name only to receive your free offer. Count on never hearing from them again. And, consider the fact that they might enter a fake name and email. If you require that they optin before they receive the free offer, you will retain quality prospects for your business. This enables you to build your customer base and to take your business to the next level.