How to set up the option to approve Subscription requests.
New subscribers may sign up by completing a web page sign up form placed on your website. Another option is when a new subscriber sends an email to listname-on@mail-list.com (where listname is replaced with the name of your list).
By turning on Approve Each Subscriber, every subscription request is forwarded to you, the list moderator/owner. Subscribers are added to your list only after your approval.
Approval Process workflow

Use the Web Interface
Log into your mail-list account at https://database.mail-list.com.
- Click Customize Your List.
- Click New Subscribers Settings.
- Click Moderate New Subscribers.
- Select the radio button for Approve Each Subscriber.
- Click Save.

Helpful Information:
Click here for more details about the Opt-In and Approval process.