I have a postfix mail server running on a Debian machine.
This server handles all incoming mail. However, I want all mail sent to a certain subdomain to be handled by another mail server running on another port on the computer.
In other words, all mail going to *@subdomain.domain.tld should go to address and port XX.XX.XX.XX:YYYY
At the moment I handle aliases in /etc/postfix/virtual but I don't see how to enter this rule there.
I should also mention, that postfix is (probably) not equipped to receive any mail coming to the subdomain at the moment. Therefore it would be great if you could explain how to get there from the start...
How can this be achieved?