I never tested this so be careful and have a backup.
All your existing mailboxes created under .xyz domain will continue to have that domain, but you can use an domain alias.
First you need to create all necessary DNS entries for the neutine.net domain, and also change the reverse DNS to that new name.
Then add the domain in the domain list and then update your mailcow.conf.
Update the mailcow.conf file and change all references to the old domain, especially mailcow_hostname
Do docker compose up -d
Check if lets encrypt container has pulled the certificates for the new domain, otherwise consult documentation for “force renewal”.
If that seems too complicated: Create a new clean mailcow with the new domain (in parallel to the old one), and create the mailboxes and use sync jobs to copy mails over from old xyz mailcow.
