Gaggle Mail (https://gaggle.email) has a free plan and it's cheapest paid plan is $100 per year. It's popular with family groups doing what you describe.
I’ve been running Gaggle Mail (https://gaggle.email) for over 10 years, and mailing lists are still very popular in certain circles. They’re especially valued for long-form discussions — legal groups, professional associations, HOAs, and similar communities still rely on them because they’re simple, reliable, and easy to archive.
That’s a neat script and one of the simplest setups I’ve seen for running a mailing list (even though I don’t understand everything the Lisp is doing).
I’m a massive fan of mailing lists and despite all the other alternatives I think for the right group of people they’re the perfect solution.
* Here comes the shameless plug *
I’m the founder of Gaggle Mail (https://gaggle.email/) which provides dead simple group email. Our customers are as far from the HN crowd as you can get; non-technical, generally elderly but they’re desperate for something simple, with few features that does just what they need - and they’re willing to pay!
There’s a real market for taking what appears as a simple technology to most techies and dumbing it down to make it accessible to a wide and willing market.
Threading can be preserved when creating a new message as long as the mailing software re-uses the same: 'message-id', 'references', 'in-reply-to' and 'thread-index' headers.
I work on Gaggle Mail which is a group mailing list provider that avoids all this by only using a From address that we control. I do think stricter addressing policies will become the norm in years to come which is why we took this approach.
I started Gaggle Mail (https://gaggle.email) just over a year ago, it's making around $400 per month and growing nicely.
I've really enjoyed the experience watching something I have sole responsibility over grow and be appreciated by the people who use it.
I set out to build something I could be proud of and other people would find useful - in those terms it has been successful. And with another year or so of growth it could provide the majority of my income.