Yo!
I was wondering if this was possible using the Email Marketing module.
I've created a User Smart Search that gets all users that have added a product to a Favorites List.
So in Email Marketing: Can I create a newsletter that generates the favorited products for any users that matches the Smart Search criteria?
So for example a logged in user adds 5 products to their favorite list and after a week they'll receive a newsletter containing these 5 products.