This episode breaks down the seismic shift in email deliverability as Google, Yahoo, and Microsoft implement mandatory authentication requirements for bulk senders. We explore the 5,000-daily-message threshold for permanent bulk sender classification and the new baseline of dual SPF and DKIM authentication coupled with mandatory DMARC records.

The discussion dives into the technical mandates of RFC 8058 one-click unsubscribe and the "death zone" for deliverability: the 0.3% spam complaint threshold. Finally, we explain how to monitor your status using the new binary "Pass/Fail" compliance model in Google Postmaster Tools to ensure your messages continue to reach the inbox.