Customers who opt-in to email marketing from your WordPress e-commerce site during checkout are added to a specified list on Campaign Monitor.
Visit campaignmonitor.com to register for an account.
Shopp is an e-commerce plugin for WordPress. Learn more about Shopp.
Yes, there are different extensions available including emailing marketing, short message service (sms) notifications, forms & reporting, help desk, and more. Please visit Optimize My Shopp.