Ask HN: Which mailing list provider to use?

Recently mailing lists hosted by AT&T research have stopped working. These lists were used by ksh developers and users, so I am looking for an alternative[1]. Since the issue I opened on GitHub did not generate much public interest, I would like to ask this question to HN crowd. Which mailing list providers do you use and why?

[1] https://github.com/att/ast/issues/1013