Please clarify category mapping

I have a blog with 14 post categories but I want to exclude 3 from autoposting. I assume that to do this I will need to add each of the categories into the category mapping. Many of my posts are listed in a number of categories. So my question, if I write a post with 2 categories will my subscribers get 2 separate newsletters; one for each category? Or will they hopefully only get one?

http://wordpress.org/plugins/autochimp/