Mailman 3
The Perfect documentation includes installation of the 'mailman' package with apt. The 'mailman' package is no longer available for Ubuntu 22. Mailman 3 is bundled in multiple packages.
This ticket is intended to give visibility to the topic.
See http://list.org/download.html and "apt search mailman" Packages are available individually, for the core, client interfaces, and web interfaces. There is a new "Suite" package, that should be available as mailman3-full, but it seems this "full" package is not yet available from Ubuntu 22 default repos.
Perfect instructions may need to specify that only Mailman Core and MailmanClient are required in Ubuntu 22 or other distros. Answers should be prepared for "will the Mailman Suite work with ISPConfig?". That is, if someone installs all of the web components, will there be any negative interaction with ISPConfig settings? Changes may be required in ISPConfig to accommodate Mailman3 package separation.