Interesting discussion. I don't think anyone pointed out to the original questioner that mailman seems to work on any number of Unix-ish platforms (since he asked for a non-Linux OS): I'm playing with it in another window on OpenBSD on Sparc at the moment.
I don't want to get into an elaborate discussion of the credit given vs. credit asked for vs. credit taken mess, except to make a couple of general comments:
Sometimes folks who should get the credit don't -- because they never asked for it and nobody really knew to give it to them.
Sometimes folks get credit for something despite their best honest efforts to disclaim it.
Sometimes it's unclear, even to the people doing the work, who should get credit for it. This gets really complicated as we build on each others' work, whether in terms of code, protocols, interfaces, or ideas.
Thankfully, most people really do make an effort to try to claim the appropriate amount of credit and disclaim any more.
---Rsk