• Registered customers are the accounts in Customers. They are targeted dynamically through segments (All Users, People who have never Purchased, subscription status, etc.) – you never need to import them.
• Contacts (Marketing > Email > Contacts) are email addresses that are not customer accounts – people you add manually, upload from a CSV, or who signed up through your newsletter form without registering. Each has a Name, an Email Contact and a Receive Email? flag.
• Lists (Marketing > Email > Lists) are groups you build for targeting. A list can contain both registered customers (added via Add Users) and contacts (via Add from Contacts, Upload Contacts or Add Contact). The list page shows Total Members, Registered Users and Uploaded Contacts and each member's Source.

When you pick a list in the campaign wizard, Sprwt sends to all its members who can receive email. A system list named Email Newsletter is created automatically for newsletter signups.