Hi all,

Following the recent discussion, I started thinking about another aspect that 
will eventually need to be addressed.

John mentioned that one open question is what "alignment" should mean once a 
message carries a DKIM2 chain containing signatures from different domains.

Today, with DKIM1, the model is straightforward: DMARC evaluates whether there 
is at least one aligned DKIM signature (or SPF), and BIMI builds on that DMARC 
result.

With DKIM2, however, the receiver no longer sees a single signer but a sequence 
of accountable participants.

For example:

i=1, d=example.com (originator)
i=2, d=list.example
i=3, d=forwarder.example

At that point, what does "DKIM aligned" mean for DMARC?

Should alignment be satisfied if any valid signature in the chain aligns with 
the From domain, or should the chain semantics introduce a different 
interpretation?

The same question seems relevant for BIMI.

BIMI is not only concerned with authentication, but also with representing the 
identity associated with the From domain. Since DKIM2 preserves the complete 
chain of responsibility rather than a single signature, I wonder whether BIMI 
evaluation should continue to follow the same DMARC alignment model or whether 
DKIM2 introduces considerations that have not yet been discussed.

I'm not suggesting a particular solution here. I'm mostly wondering whether 
this is expected to be part of the future DMARC/DKIM2 interoperability work 
that Wei mentioned, or whether the WG already has a preferred direction in mind.

Regards,

Pietro Mauri
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