[MM3-users] How to debug DMARC check?

Gilles Filippini writes:

Now I have added an internal docker network 172.29.0.0/16 and configured exim4 to relay from this internal network only. Since this network is not accessible from the host, IPv6 spammers are blocked (*).

But since this modification mailman alters every emails with DMARC mitigation.

Any hint how to debug this issue?

Mailman has three levels of DMARC mitigation: never, as-needed, always. If you have it set to as-needed, Mailman will look for the DMARC policy as the DNS TXT record for _dmarc.domain-of-from.tld. If it can't get a reply it assumes the worst (p=reject) and applies the mitigation.

You can

1. set mitigation to never
2. give Mailman a way to connect to a DNS server.

Steve