[MM3-users] Re: Delivery to mail@domain.tld failed with code 444, [Errno 111] Connection refused

I identified the restriction

smtpd_sender_restrictions = reject_unknown_reverse_client_hostname which blocks the connection from mailman in postfix. I have no idea why mailman sends its mails by IP instead by containernam/hostname as before. Probably this relates with IPv6 activation ....