We are using Mailgun to send our emails as SMTP relay.
When I try to send some email from one address to another in the same domain, I get an error in Postfix since the bounce address doesn’t exist in our domain… But bounce address isn’t a fixed address, Mailgun changes it for each message, so I can’t configure this sender in our Mailcow server as an alias…
NOQUEUE: reject: RCPT from mail28.static.mailgun.info[104.130.122.28]: 550 5.1.0 <bounce+f89f7d.2a3c63-contato=treasuryesc.com.br@treasuryesc.com.br>: Sender address rejected: User unknown in virtual mailbox table; from=<bounce+f89f7d.2a3c63-contato=treasuryesc.com.br@treasuryesc.com.br> to=contato@treasuryesc.com.br proto=ESMTP helo=<mail28.static.mailgun.info>
Any suggestion how to solve this?