I’m using mailinabox v56 on a dedicated Ubuntu 18.04.6. When I usually send emails, SPF and DKIM/DMARC are valid.
However, if I send emails from other servers via the relay setup, SPF and DKIM/DMARC fail. Although the emails are sent and received. They will end up in spam though.
Is SPF/DKIM/DMARC supposed to work when relaying? If so, what could be wrong in my setup? I didn’t customize mailinabox with the exception of a changed SSH config, a different index.html in the webserver and a backup job.
These standards are created so that these tests only pass when the domain is explicitly configured to support the relay. So it isn’t something directly to do with the relay, itself.
This shoudln’t be an issue with the configuration of the system. You will need to configure the DNS records to support sending from the relay.
Do you have any hints which DNS changes are required? The relay setup documentation doesn’t mention any DNS changes.
My understanding of the relay was that relayed emails are sent from the mailinabox. So a receiving server would think the email was sent by the mailinabox server, not the server the email originated from. In that case, DNS changes wouldn’t be necessary, as long as the mailinabox can send emails and pass the tests.
It is easier to resolve your problem with DNS information provided. You can even send me a PM if you want to share. Otherwise, it is up to you to make sure that your SPF records, DKIM signatures, and DMARC are in alignment. (Note that the provided information does not state a DKIM test failure.)