DMARC doesn't really do much to prevent general spam. It prevents spoofing the from address, which provides some protection against phishing, but if the email is from the domain it claims to be, it can pass DMARC whether or not it is spam.
Indeed. Ultimately we're still relying on blacklists, Bayesian filters, and hueristics to detect actual SPAM.
Indeed. Ultimately we're still relying on blacklists, Bayesian filters, and hueristics to detect actual SPAM.