1. Navigate to Admin | Configure Fields | Prospect Fields.
2. Click + Add Custom Field.
3. Name the field Opt in, and fill out the remaining form fields.
4. From the Type dropdown, select Radio Button, and enterOpt in for the value.
5. Create a form that contains the new field.
6. Send a list email that includes the link to the form to ask prospects to opt in to your list.
7. To remove prospects that haven’t responded or opted in, create and run an automation rule with the following criteria.Prospect list [is member of][email list name].Prospect custom field [isn’t][Opt in].Completion action: Change prospect default field [Do Not Email] to [Do Not Email].
8. Prospect list [is member of][email list name].
9. Prospect custom field [isn’t][Opt in].
10. Completion action: Change prospect default field [Do Not Email] to [Do Not Email].