I used to do a newsletter (on paper, pre-computer era) and subscribe to a couple. They were tightly focused in terms of content, for a specific readership. I'm not sure that's what you want to do here, unless you only want to write about a small group of topics and never vary.

Or you could do as contrarywise suggests, and grow it.

I'm uncertain how different a newsletter in that sense would be from a blog. Or, actually, from this journal.