I've installed and activated the plugins Git repositories, Subversion repositories and Mailman in Virtualmin. All Virtual servers got them as "Allowed features for servers".
When I login as a virtual server administrator I can't find the plugins under Services (Virtualmin Framed Theme or Authentic Theme) so it isn't possible for the administrator to create or administrate Git, SVN repos or mailing lists.
When I look back in my old manuals that I wrote for the administrators I wrote:
When I wrote that everything worked and it was written 12 Sept 2012.
When I try to browse to the URL http://host/virtualmin-git/ I get: Access denied : User xxxxx is not allowed to use the Virtualmin Git Repositories module
I will answer my own question.
The answer is found here: https://www.virtualmin.com/node/28589
"Try going to System Settings - Server Templates - Default settings - Administrators Webmin Modules, and make sure that access to the mailman module is enabled."