[Mailman-Users] LIST-JOIN at DOMAIN request sent to subscriber-ownder at domain.com

[Ki Song]

Something weird is happening.

When I subscribe to a mailman list by sending an e-mail to
somelist-join at somedomain.com from subscriber at domain.com

it looks like the request is received by the mailing list, but then the
confirmation email is sent to subscriber-owner at domain.com
instead of subscriber at domain.com

Therefore, no user is able to subscribe.

What could be causing this?