All this discussion of Majordomo and Listproc reminds me of the
saga of MLManagement here at Eskimo, where I maintain a list
(I'm just a user, not a sysadmin). When MJ became too much of
a burden on Eskimo's resources, through inefficient delivery
and lax dead-subscriber autoremoval, they tried Listproc.
After fighting with LP for nearly a month, they finally
switched to SmartList, which is built around Procmail.
That was many years ago, maybe 1996 or 1998 and the system has
been rock solid ever since. I can't speak for how hard it is
to do the initial install, but knowing Procmail, I suspect it's
not very hard. I know some of Eskimo's requirements were runtime
efficiency, as they're a small ISP, and security.
The best feature, from my list maintainer's perspective, is its
ultimate configurability. With a few simple Procmail recipes I
can do anything I've ever wanted to my list, from removing
free-mailer advertisements, blocking html posts, moderating
individual subscribers' posts, passing posters' test messages
back to the poster without sharing them with the whole list,
stripping excess quotation from the digest version, etc.,
as well as great spam blockage.
The original poster wanted open source; you can't get more
open source than SmartList... :)