(Solved) Subdomain mx / sending (DMARC)

Dear Community,

I want to run on a subdomain my own mailman installation. I have successfully build everything up and it runs smoothly. But the DMARC settings nack me - if the recipient takes care of such settings the mail will be blocked.

My question now - how can I run a Mail system on the external System for a Subdomain?

box.example.org holds example.org. The Subdomain mailman.example.org points to a different host, having A, AAA and MX records set up in the custom DNS Settings.

Receiving emails is possible, but because the subdomain is not excluded from DMARC and/or mailman.example.org is a valid sender the mailman server can’t reach all recipients.

How can I configure either the DMARC settings to make mailman.example.org valid or make it possible to relay all messages via the MIAB. With the second option - creating one account/alias for the subdomain on the box MIAB will overwrite the MX Records added adds itself with the priority of 10. What makes the MIAB a Backup/secondary MX for that Domain what is not wanted (as I would need to configure fetchmail for that box to get even the mis-redirected messages to the lists.

// Edit 1

When I try to override the DMARC Settings the result is something inconsistent. Because the Domain holds two DMARC Records now …

I’ll resolve this myself.

After I had identified how I’m able to overwrite some settings I was able to make a subdomain using a dedicated mail system.


I needed first the A/AAAA Records for the host, followed by the MX host followed by overwriting the SPF Record that is created by MIAB followed by overwriting the DMARC Record from MIAB.

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.