> anyone can send an email with any "from" address, and filtering on people/domains in the "from" field is basically pointless if you want to catch spam.
Isn’t this the exact thing that DKIM is designed to fix?
This was a response to a complaint about not receiving emails from some "people/domains" even when whitelisted, and I highlighted how this can be hard for a service to detect reliably.
So yes, DKIM will help a receiving server know for sure, but a receiving server still needs to accept emails from non-DKIM-enabled servers, and perhaps that's why whitelisting didn't work for the parent.
So yes, DKIM will help a receiving server know for sure, but a receiving server still needs to accept emails from non-DKIM-enabled servers, and perhaps that's why whitelisting didn't work for the parent.