Re: [Uta] Benjamin Kaduk's Discuss on draft-ietf-uta-smtp-require-tls-07: (with DISCUSS and COMMENT)

[Viktor Dukhovni <[e-mail]>]

On Tue, Feb 26, 2019 at 03:26:05PM -0800, Jim Fenton wrote:

> >    If a REQUIRETLS message is bounced, the server MUST behave as if
> >    RET=HDRS was present as described in [RFC3461].  If both RET=FULL and
> >    REQUIRETLS are present, the RET=FULL MUST be disregarded and MAY be
> >    transformed to RET=HDRS on relay.  The SMTP client for a REQUIRETLS
> >
> > If the MAY is not taken, will the next hop be obligated to detect that this
> > is a bounce and apply the preceding MUSTs?  If not, perhaps this also
> > should be a MUST?
>
> It seems like it should, yes.

Actually, absolutely not.  It is not the job of email *relays* to
modify the message content, and they must not be obligated to do
so.  Message modifications break DKIM signatures, and require
content processing logic that relays are not expected to support.

The bounce is constructed as a new message at the server that
encounters the initial delivery problem, it is *only* at *that*
point that the decision can be made to include or exclude the
original message body in the bounce.

-- 
	Viktor.