NewsLetter Builder  is a concept I developed in 2015 and currently being ported to WordPress (with more bells and wisles).
Its a composer to create newsletters in minutes: not so much the typing, more like inserting Blog-posts , pages and products that have a featured image setup

Backend:
creation: sertting and header+footer setup

frontend:
1) archive a shortcode for all available newsitems: [newsbuilder_news] and links to view.


2) subscription shortcode