A friend and former cow-orker of mine (who is also a big open source advocate) has ran FreeLists [0] for, I dunno, 15 years or more. I don't know that it gets much easier than that.

> FreeLists provides the internet community with Free, no-hassle, high-quality mailing lists. We don't use advertisements and we don't charge for higher-than-a-certain-volume lists.

[0]: https://www.freelists.org/about.html