DKIM2 draft -07 adds a post-quantum signing algorithm and requires an authentic From

The IETF DKIM working group posted two DKIM2 revisions dated October 18, 2026: version -07 of the core specification, draft-ietf-dkim-dkim2-spec, by Richard Clayton (Yahoo), Wei Chuang (Google) and Bron Gondwana (Fastmail), and version -01 of the companion DNS document, draft-ietf-dkim-dkim2-dns, by Wei Chuang. They are the first revisions of either document since late summer; our report on spec -04 covers the earlier state. Both remain Internet-Drafts, not standards.

A post-quantum signing algorithm

The biggest new item is a third signing algorithm, mldsa44-ed25519-sha512. It signs the message hash with both ML-DSA-44, the post-quantum algorithm standardized in NIST FIPS 204, and Ed25519, and places the two signatures one after the other. The DNS draft explains the pairing: ML-DSA protects against a future quantum computer able to break RSA and elliptic-curve keys, and Ed25519 is a backstop in case ML-DSA turns out to have an undiscovered flaw. The DNS draft adds a matching k= key type.

The two drafts currently word support differently. The core spec says Verifiers MUST implement all of its algorithms. The DNS draft keeps rsa-sha256 as the only MUST for now and says Ed25519 and the new composite algorithm will move from SHOULD to MUST once DKIM2 is complete. Both drop legacy rsa-sha1.

The From header must be "Authentic"

Draft -07 adds a section requiring From header fields to be Authentic. The draft defines that as a relaxed domain match between the domain in the From address and the signing domain (d=) of the relevant DKIM2 signature. If a forwarder replaces the From header, the next signature added must match the new From. In practice this builds a DKIM alignment-style check into DKIM2 itself rather than leaving it only to DMARC.

Other changes in -07

• The donotmodify and donotexplode flags were removed from the core spec. A separate Sender Policy draft (draft-chuang-dkim2-sender-policy, revised to -04 on October 19) still describes them.
• Verification text was reworked to state only how to check for a validly signed message, with DKIM Replay handling rewritten.
• New sections cover internationalized email (EAI) and security considerations.

What senders should do now

Nothing changes in production yet. Classic DKIM remains what mailbox providers check, and the DNS draft says DKIM and DKIM2 are expected to co-exist. Our analysis: the Authentic From rule means a domain that signs with an ESP's shared domain rather than its own would not meet DKIM2's requirement, so aligned custom-domain signing is worth having in place today. Confirm yours with our DKIM checker.