Mailman list names have to be globally unique.
Under Virtualmin > System Settings > Features and Plugins > Mailman > Configure, I have set "Append domain name to list names" to "Yes".
With this option set to "Yes", Mailman says subscribers should send messages to listname_domain.name@domain.name
But messages sent to that address are being rejected as follows:
Recipient address rejected: User unknown in virtual alias table
Postfix Mail Aliases lists an alias: listname-domain.name > Program /usr/lib/mailman/mail/mailman post listname_domain.name
Messages sent to listname-domain.name@domain.name are likewise rejected.
Why does this happen?