Email Server Security: How PostMTA Handles SPF DKIM DMARC

Email authentication is now mandatory for Gmail and Yahoo inboxes. PostMTA handles SPF, DKIM, and DMARC automatically. SPF authorizes sending servers, DKIM adds cryptographic signatures, DMARC enforces policies. As of 2024, bulk senders must have valid SPF/DKIM, DMARC policy of at least p=quarantine, bounce rates below 5%, and one-click unsubscribe. PostMTA handles all of these. https://postmta.com