I am unable to create mailing lists with specific names:
and it fails with an error:
Error: Unable to create list: listmng failed: listmng: Invalid/prohibited list name 'aaa-owner' listmng: Error: cannot create new list: is Mailman configured properly?.
The issue is reported with id #PPPM-864 to Service Team. It is going to be fixed in Plesk microupdate or new Plesk version. You may follow up feature implementation status using aforementioned resources:
https://parallelsnetwork.com/ - public roadmaps for partners;
http://sp.parallels.com/mailinglists/subscribe/ - marketing news and important announces;
http://kb.plesk.com/subscriptions/index.html - knowledge base, each product update comes with corresponding KB article;
http://sp.parallels.com/products/plesk/rss - RSS feeds.