Ok so I apologize if I am essentially asking the same question, but, I just got a request from a client to build a backend for an existing site, where they can view "applications" (submitted by using a form that submits to the database I will setup on their site). But they want to add a newsletter email functionality and I was thinking about PM. So if I use a basic user registration, using the tools I already have from WA, I couldnt just integrate PM into this backend? They would have to login in again to PM?