mailman - 1:2.1.29-1+deb10u5 main

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.
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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.
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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.