Great stuff as always Josh Spector ! This point is definitely true in my experience running both paid and unpaid newsletters.
Blogging Guide offers value up front be creating access to digital products useful to bloggers and content marketers.
You are definitely correct that people do not want to be inundated with more emails — they want high quality, unique and actionable content.
Once you figure out how to provide value, you really only need to learn a few tricks to scale your newsletter and increase subscribers: