Why Your WordPress Emails Vanish: SMTP, SPF, DKIM and DMARC
WordPress tells you the mail was sent. The customer never got it. This is a working guide to the four places WordPress email deliverability actually breaks: PHP mail() transport, SPF lookup limits, DKIM alignment, and DMARC policy. Includes real diagnostic commands, a troubleshooting order, and what changed now that DMARC has moved onto the IETF standards track.