Ask HN: What is something you like or don't like in a newsletter?

I am currently unsubscribing from lots of design newsletters, mostly because it doesn't give good contents anymore. I don't care what's the latest design trends or "how to" something. I care about something that will likely still relevant for the next year, like: Why we need to use small caps or text figures correctly.

So, I had an idea to build a design newsletter and curation the way I want, like newsletter from Nielsen Norman Group, or UX Thoughts by User Interface Engineering. No "5 Design Trends in 2017" nor "5 Design Tips from Design Leaders", just good content.

Do you have any advice? What is something you like or don't like in a newsletter?

Thank you!