You can optionally feature a sign-up form to your mailing list on your webpage (your public profile page on interests.me). This enables you to send people to a specific page to sign up to your mailing list.
When you create a mailing list, if you have chosen to make it 'public' - ie you're allowing members of the public to sign up to it - a sign-up form will automatically appear on your public profile page to invite members of the public to sign up.
When members of the public opt to join your mailing list, they are sent an automatic email to ask them to 'double opt-in'. If they don't click this email to confirm that they want to sign up, they won't be added to your mailing list. This ensures that no-one signs up someone else to your list and that all your sign-ups are genuine.