If you want to send a welcome email to your recently added subscribers to your site, you can do so using a combination of our API's and Autoresponders.

You would first need to create a Autoresponder for the contact list you are going to add the contacts to. You then need to create a "zero" day email which you want to send to your subscribers.

When you add the subscribers using the API method listAddContacts, the "zero" day email will be sent to the contacts.

You can also use personalization in the email, if you have given the extra field information when saving the contact using the API.