I would like to slowly migrate an old mail server to mailcow. The most domains I have already in mailcow, only one (the most important one) ist missing. The easiest is, that I create the same domain in mailcow and all mailboxes, and add sync jobs. This works also, when the DNS points still to the old server.
The problem with that is, that mailboxes from mailcow tries to send emails to the mailbox from the old server, they don’t reach the target. Instead mailcow tries to put them in the new mailbox on its own server.
Is there a way, to disable one domain in mailcow, and only use it in sync jobs, but mails still send to the old server?