Yes, you need to look into permission based marketing program. There are services such as Constant Contact, Intellicontact and MailerMailer that can help you capture and manage E-mails.
Using those services, you can put a very brief form on your home page and any emails entered will be automatically added to your list. Then you can stay in touch with those folks and build a long-term business relationship.
The services also automatically manage "bounces" unsubscribes, etc. And yoy get a host of reports so you can track the effectiveness of your campaigns.
Hope that helps.
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