Re: "From" at beginning of line gets escaped (was: Re: Testing Discourse for Debian)
The following is the text of an email that got generated as I tried to make a
comment on the bug report you filed. I'm not sure how soon the comment might
appear on the bug report, so I decided to add it here as a reply.
I guess I should add one thing, that I presume the people who deal with the
bug report will recognize: I don't know how much legacy software would be
affected if the described behavior changed.
<quote>
#956806 lists.debian.org: changes messages with lines starting with "From",
breaking DKIM signature
From: rhkramer@gmail.com
To: 956806@bugs.debian.org
Date: Wed Apr 15 11:22:37 2020
Aside: This may be the first time that I've responded to a Debian bug -- I
expected that when I clicked on reply, I'd be given a text box on the bug
report web page to make my comment, instead, I'm apparently writing an email.
I presume this will get to the right place.
Hmm, I probably should not respond to this as I cannot do a complete or maybe
even an adequate job.
I do know this. When mail is stored in an mbox file, From at the beginning of
a line (admittedly with other requirements after the From) can indicated the
beginning of an mbox header, which separates one email from another.
A "real" mbox header has other stuff on that line that can and should be parsed
and considered to determine if it really is an mbox header, but some software
in the email chain typically escapes a From at the beginning of a line (by
prefixing it with a >, iirc) to, well, distinguish it from an mbox header and
make it easier on the mbox software somewhere in the chain.
I'd hesitate to suggest that "feature" should be disabled, there are probably
lots of places where that would cause a problem.
I don't know if there is another solution.
</quote>
On Wednesday, April 15, 2020 10:42:10 AM Ansgar wrote:
> On Wed, 2020-04-15 at 20:18 +0900, Charles Plessy wrote:
> > as we discuss about proper quoting, I would like to take the opportunity
> > of Ansgar's email to note that each time a line starts with "From" in a
> > plain text email, something in the pipeline that delivers emails (at
> > least to me) inserts a ">" sign, which is then misinterpreted as a
> > quotation character. See above…
>
> Hmm, indeed. And I was wondering what was breaking the DKIM
> signature...
>
> Looking at the headers of my mail I find:
> | X-Amavis-Spam-Status: No, score=-12.6 required=4.0
> |
> | tests=DKIM_INVALID,DKIM_SIGNED,
>
> with an invalid signature, but below that (earlier in the pipeline)
>
> this signature was still valid:
> | X-Amavis-Spam-Status: No, score=-8.863 tagged_above=-10000 required=5.3
> |
> | tests=[BAYES_00=-2, DKIM_SIGNED=0.1, DKIM_VALID=-0.1,
> | DKIM_VALID_AU=-0.1,
>
> So it looks like the lists setup somehow breaks this...
>
> I reported this problem as https://bugs.debian.org/956806
>
> Ansgar
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