I have a setup with 1 pure mail server, lets call it mail, and 1 web server, lets call it web.
When web sends out email to an external server it uses mail as relay. Both servers use postfix. mail has a MX record and is the the official mail server for the domain, web has no MX record and on this server postfix works basically as a mail client only.
The problem: When web sends email via mail, and that email is rejected by the remote mail server, it gets bounced back to mail which forwards the NDR to web. What I'd like to have is that mail accepts and stores the bounce emails.
What postfix options do I need on both servers to achieve this?