mailman 1:2.1.29-1 (amd64 binary) in ubuntu focal

 The GNU Mailing List Manager, which manages email discussion lists.
 Mailman gives each mailing list a web page, and allows users to
 subscribe, unsubscribe, etc. over the web. The list manager can
 administer his or her list entirely from the web.
 .
 Mailman also integrates most things people want to do with mailing
 lists, including archiving, mail <-> news gateways, and so on. It
 has all of the features you expect from such a product, plus
 integrated support for the web (including web based archiving),
 automated bounce handling and integrated spam prevention.
 .
 Note that this package contains the legacy (2.x) branch of Mailman.
 All new development happens in the Mailman 3 suite, available in
 Debian via the mailman3 metapackage.