Correct, which is why Antivirus gateways need to have a relationship with the
eventual recipient. If you run an antivirus gateway and remove the content,
then forward it on, you're in a state of sin.
Maybe you're really a good actor, just cleaning viruses.
Maybe you're a scumbag, replacing the content with your own material.
Nobody can tell, so they have to trust you. So you'd better be on (as Richard
says) their Christmas Card list.
Bron.
On Wed, Sep 9, 2026, at 19:46, Vittorio wrote:
> Hello Bron,
>
> Allen Robinson stated on this list that null recipes "reintroduce the
> concept of trust to DKIM2" and cited this as a strong reason not to
> support them. Your description ("switches from evidence based to trust
> me") confirms his assessment. The mechanism the specification relies on
> for antivirus, DLP and encryption gateways is, by its authors' own
> acknowledgment, a reversion to the trust model DKIM2 was designed to
> replace.
>
> Regards,
> Vittorio Moccia
>
> Il 2026-09-08 15:11 Bron Gondwana ha scritto:
> > On Tue, Sep 8, 2026, at 17:47, Vittorio wrote:
> >
> >> On malware I agreed, the libraries aren't the exposure. But I still
> >> haven't seen how a body recipe avoids carrying downstream exactly
> >> what
> >> an antivirus gateway stripped. Antivirus usually operates at the
> >> edge,
> >> but the same edge serves both local reception and onward relay to
> >> other
> >> systems.
> >
> > This is what the null body recipe is for. It is canonically
> > impossible to both suppress the data the antivirus gateway stripped
> > AND make it possible to recreate the previous message in a way that
> > the hash of an earlier Message-Instance header will still match.
> >
> > The alternative, as ARC has demonstrated, is a trust-based system
> > rather than an evidence based system. The null body recipe is just
> > that, a way that switches from evidence based to "trust me".
> >
> > Bron.
> >
>
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--
Bron Gondwana, CEO, Fastmail Pty Ltd / Fastmail US LLC
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