Topic
Mail delivery and authentication: DMARC, MTA-STS, DANE and TLS reporting, and Interspire Email Marketer integration notes.
5 engineering notes.
- Spamhaus will enforce HELO and reverse DNS from November 2026: check every sending IPSpamhaus now requires forward-confirmed reverse DNS and a HELO name that resolves to the sending IP. A stock Postfix container announces EHLO localhost.
- MTA-STS, TLS-RPT and DANE: mail transport security with Postfix 3.10Postfix 3.10 adds TLS-RPT reporting for DANE and MTA-STS. What the three mechanisms do, how to enable reporting, and what the implementation does not cover.
- DMARC is now RFC 9989: what changed in May 2026The DMARC specification was replaced in May 2026. The pct tag is gone, np and psd arrived, and policy discovery no longer uses the Public Suffix List.
- Disable SEO URLs in the Spinning addonTurn off the Spinning addon's SEO URL rewriting by changing one constant in its configuration file.
- Add subscribers using the Interspire XML APIImport or add subscribers to any Interspire Email Marketer contact list with the XML API exposed by the Installer addon.
Related service: Email Infrastructure & Deliverability →
