Mailman
From ArchWiki
Python based mailing list manager
I had some quick notes to help get the package working with postfix.
I had to do:
# groupadd -g 80 mailman
# useradd -s /no/shell -d /no/home -g mailman mailman
Then the ./check_perms -f script would run and I was off
More to come if I have any problems.