DKIM and DMARC are not anti-spam measures, they are anti fraud measures.
Signing email with DKIM, and mandating DKIM alignment via DMARC is a very powerful method for preventing unauthorized email from your domain.
Signing email with DKIM, and mandating DKIM alignment via DMARC is a very powerful method for preventing unauthorized email from your domain.
If I want to be sure that an email came from a certain person, I ask for a PGP signature on it.