I've recently noticed that some of the incoming mail is being dropped, from certain domains.
I had two mx records,
1. my smartermail server with greylisting
2. a backup mx server provided by my domain registrar.
What happened is that because of the greylisting some of the mail would go to the 2nd mail server.
This mail would then be send to my smartermail server from the 2nd mail server.
This mail appears to be dropped because it came from my 2nd mail server and not from the original mail server.
I assume this happened because of dmarc and or spf rules.
I've currently disabled greylisting, but if my mail server go's down those mails would still be dropped.
How can I configure a server as a trusted backup mail server in smartermail? (so that dmarc and spf rules are ignored when mail comes from that server)