ConstantContact is a 3rd party service provider that allows stores to manage email lists of clients. This allows WebStore owners to issue email communications to signed-up customers.
Where does the email information come from?
###1) newsletter form
Customers are able to subscribe to the newsletter by providing their email address on the home page.
###2) mailing list pop up
You can enable email pop up window on your home page in WSM to allow customers subscribe to your mailing list.
###3) checkout page
Customers can also subscribe to your mailing list from the checkout page
Your WebStore requires customers to sign up in order to buy items. As part of this signing up process they are required to give an email address