When I had the idea on the series about The Opinionated Engineer, I figured maybe that’s something worth setting up a newsletter service over. That said, after some consideration, I just thought that I didn’t need anything too complex and decided to roll my own because “how hard could it be?”. As far as I can tell, I think it’s working fine so far(?) and took me around one whole day to put the whole thing together from my couch. You can find all of it’s source code here on GitHub.
Existing newsletter services
Aside from Substack, pretty much all other services provide it with a "freemium" model where you are charged based on the number of subscribers (regardless if they are paid). Admittedly, I doubt my newsletter would get to that point (I try to not take myself too seriously lol) but I also didn't need most of the things those services are providing. Not to take anything away from them, they all seem really useful if someone is doing that for a living, but I mostly write for fun and as a way to do some knowledge preservation (future self-reference) with the sharing part mostly being a bonus.
As for Substack, I didn't look too deep into things and while they don't have the best of reputation, their product seems to fit my use case best where I won't have to pay anything ever unless I started having paid subscribers. That said, I thought I didn't need something as fancy but just something simple that goes with my personal blog.