I'm new to Salesforce Marketing Cloud. I am going to be creating a landing page (outside of marketing cloud) that will have a sign-up form for our e-newsletter. How can I automatically importing email addresses from subscribers who sign-up for my e-newsletter via this landing page, to an existing subscriber list? Do I use a web service API? AMPscript, etc?
I have done my research and do not have a clue! :(