Please note, Plesk has supported the version of Mailman provided by OS vendor by default.
The Mailman 3 is shipped by default on Ubuntu 18 and Debian 10.
Please keep voting if this request is still actual for you.
An error occurred while saving the commentelias commented
Considering you(Onyx) is seeing plesk as an all in one solution to host and manage websites and webspace/domains/email by sellers/resellers/customers as well as the hole basesystem(updateprocess), it would be fortune to implement the state of the art softwarebranch of a already implemented software, which is updated to fullfill the needs of a changed email verification standard(dkim and more), as well as the updated webinterface. But the most important point i have to mention is the data storage, maillist management changed to mysql, which we have already on our plesk servers and gives us improved possibilities to implement mailman in our products.
thx in advance