To set up a mailing list within CoreCommerce, you will first need to enable the Newsletter feature. Here's how:

1. Go to Marketing   > Newsletter link at the bottom of the blue mega menu.

2. Make sure the Newsletter feature is set to On > click Save)
3. Go to Mailing Lists < Click to create new list

You will see the following options:

Mailing List Name - This name will be used in the admin and will not be displayed to customers
Mailing List Public Name - This is the name that will be displayed to customers
Active - If this is checked, then this mailing list will be active and customers can sign up for it on your storefront
Checked by Default - If this is checked, then the "join mailing list" option on your store's checkout will be checked by default

When done, click Save.If you want to add all customers to your new list, click the Assign link

If you want to assign individual customers to a list, you can do this by editing each customer's account or by running a customer import