Option to automatically send email campaign to new emails?

[viaoahu]

Does anyone know a way to have your account automatically send a welcome e-mail to all new e-mail sign-ups?

Right now we use SquareSpace for our website.  If we put in a Square e-mail collection tool like a Hosted Sign-Up Page or an Embedded Sign-Up Form, how can we make sure that those new emails automatically receive an e-mail from us (we want to send each person a welcome and coupon when they sign-up)?