This is what mailinabox does (https://mailinabox.email/) to combat spam and it has worked remarkably well. In the few years I've been running my own mail server I have received ZERO spam in my inbox. For more info, the technique is called greylisting https://postgrey.schweikert.ch/. - Source: Hacker News / almost 2 years ago

I've used Postgrey, for Postfix, and it's greatly reduced my spam. However, first emails from new folk are delayed a bit. https://postgrey.schweikert.ch/. - Source: Hacker News / almost 2 years ago

Not to be confused with the GreyList service for Postfix - Postgrey. Source: over 2 years ago

There's the problem then. Try and figure out whats not configured properly. You can also test the domain at https://dmarcian.com/ Check you emails from Apple and see make sure your DNS settings match what Apple sent you and also set a DMARC policy, even something basic like v=DMARC1; p=none would do for the time being. Source: 11 months ago

I have published a DMARC record a week ago using the generator at https://dmarcian.com/... I have published SPF and DKIM, which both show as being valid for my domain, but DMARC doesn't show up. I have tried configuring it different ways, adding and deleting, and nothing will get these checkers to show that it's valid. Source: over 1 year ago

Excellent response. I'd also add using https://dmarcian.com to help check along with mxtoolbox.com. Source: over 1 year ago

This is a screenshot from Instantly. Tried using the checker on dmarcian.com as well and it gave me the same error. Source: almost 2 years ago

It's been a few days since I've configured the SPF/DKIM on my domain but the DMARC I put in isn't working. I snagged a record from dmarcian.com. Source: almost 2 years ago