What is your business goal through sending this newsletter?
Seems like your ICP (ideal customer profile) is too broad. – there are 1000s and 1000s of tech savvy digital marketers in the world.
What industry do you want to target? What size companies (enterprise, mid-size, small business)? What types of digital marketers (content, digital, social, demandgen, etc)?
You should be focused on subscribers who align with your content, and not necessarily shoot for a certain amount of numbers in certain amount of days.
Good luck!