Andreas Barth writes:
Distribution packages have their own up- and downsides.
I'm far from absolutist about distro packaging of Mailman, but historically, the downsides have very much outweighed the upsides for most users who come to us on these lists, unfortunately. It took many iterations of Mailman 2 at Debian to get to the point where I was willing to use the Debian packages at all, and for Mailman 3 I've never used them. Even Brian Carpenter's Install Guide avoids Debian's Mailman packages.
Of course, how they are done is to be discussed with the distribution, so: if something is wrong with a debian package, please follow the instructions on bugs.debian.org on reporting bugs.
This certainly is the definition of good citizenship. I hope all distribution users will file packaging bugs with their distros, and take it in good humor when we tell them, "works for me, so you should ask <distro> about it."
They have the disadvantage that they're stable for some time
If people have been using Mailman 2, they have had a rather better experience for the last few years, though. Since we only fix security issues in Mailman 2, Mailman itself is stable, and to the extent that I pay attention, I think Debian at least has been prompt about tracking Mailman 2 releases. Not so for Mailman 3, though.
If they have all the features someone wants,
But this is precisely the problem for Mailman 3. Mailman 3 is not feature-complete compared to Mailman 2, and even two years ago it wasn't close. (Sorry!) Yes, if all you want is a vanilla mail exploder, maybe with a footer added, Mailman 3 is great. But then there's no need to upgrade to Mailman 3 from Mailman 2, and if you're happy being distro-bound, you'll have a better experience with Mailman 2.
I'm sure there are quite a few Mailman 3 admins happy with their distro releases from 2 years or 6 months ago. But to someone who comes to us asking for advice, I am definitely going to recommend the Docker containers or a venv or /usr/local installation, because I expect that kind of user to be back for more advice in the future.
Steve