I recently moved my site from a host that provided Mailman 2.1.5 and Plesk 8.1 to one that provides Mailman 2.1.9 and Plesk 10.1.1.

I manually created 55 lists on the new host through Plesk, and populated them in the Mailman admin. All of them have the same two emails in the -owner field, which were also the same ones used for the old lists on the old host.

My problem is that emails sent to both the -owner and -request addresses bounce back with the message that that address doesn't exist.

Interestingly I tried to manually created -owner and -request addresses for one of the lists (news@domain.org) via Plesk, and was prevented with the message that news-owner@domain.org and news-request@domain.org were already in use. So Plesk thinks they exist -- but trying to send anything to them fails.

I am not a Linux guru. How do I go about debugging this?