I was trying to gather customer email but it was not enough because the amount is little here that is no way I can help get the customer's email.
@davidpnot, your question is not so clear & I think this topic might not come under SEO. But any ways let me ask you something, how are you collecting email id's? Through services like mail chimp?....
I'm siure this base of tips will help you - http://www.verticalresponse.com/blog/change-up-your-newsletter-get-more-clicks/
You can use aweber they have a $1 trial at the moment... Easy to set up, and easy to place forms, pretty much copy and paste...
You can use optin subscription box plugin to collect email addresses and integrate them with mailchimp, Aweber, Getresponse etc.