BlueOnyx has since long used Majordomo as a mailing list manager. However, Majordomo is pretty aged and wrinkled and there are better solutions around such as Mailman, which is still actively maintained by its developers.
So we decided to switch BlueOnyx to Mailman with the BlueOnyx-5.6-20110618.iso image release. To not break any existing mailing list installs, we switched the Mailman support into a different package, named "base-mailman", which - on an existing box with base-maillist (Majordomo) - will not install by itself.
If you want to switch an existing server from base-maillist to base-mailman, you can do so by following these instructions. But keep in mind that you should NOT do so if you're actively using any Majordomo mailing lists on that server:
1.) Remove Majordomo:
rpm -e --nodeps majordomo
2.) Find all "base-maillist" RPMs and remove them:
rpm -qa|grep base-maillist|sort|xargs rpm -e
3.) Install the new modules:
yum install mailman base-mailman-am.i386 base-mailman-capstone.noarch base-mailman-glue.noarch base-mailman-locale-da.noarch base-mailman-locale-da_DK.noarch base-mailman-locale-de_DE.noarch base-mailman-locale-en.noarch base-mailman-locale-en_US.noarch base-mailman-locale-ja.noarch base-mailman-locale-nl.noarch base-mailman-ui.noarch
This goes all into one line!
4.) Restart some services:
That should do the trick. If you're logged in to the GUI, log out and log back in. Then you can test the new Mailman GUI administration pages.
Additional note: If you are actively using Majordomo mailing lists, you can use CMU to migrate these lists. If a cmuExport contains a Majordomo mailing list and is imported on a box with Mailman, then the list will be created as Mailman mailing list. The list of subscribers and most of the list settings will be kept. But you will loose all old messages.
If you are unsure if your server is using Majordomo or Mailman, check "Software Updates" / "Installed Software" on a fully yum updated BlueOnyx server. It will report there if Majordomo or Mailman is installed.