no more subject prefix for xetex mailing list

[Julian Bradfield]

On 2019-03-05, Zdenek Wagner <zdenek.wagner at gmail.com> wrote:
>> > And the last thing, setting of DMARC at tug.org is wrong, the DNS
>> > query returns the SPF record, not the DMARC record.
>>
>> No, it isn't wrong - there is no setting for DMARC.
>> A dns query for _dmarc.tug.org TXT records returns two records:
>>
>> _dmarc.tug.org.         8555    IN      CNAME   tug.org.
>> tug.org.                8555    IN      TXT     "v=spf1 a a:freefriends.org mx:freefriends.org a:fencepost.gnu.org include:_spf.google.com ~all"
>>
>> tug.org has a wildcard CNAME *.tug.org -> tug.org (which strikes me as
>> bad practice, but not wrong).
>>
>> DMARC does not specify whether CNAMEs should be followed, but even if
>> they are, DMARC only looks at valid DMARC records.
>>
> Yes, there is CNAME but it refers to a SPF record, not to DMARC
> record. DMARC should contain a different type of information with a
> different syntax.

It seems you understand the DNS no better than DMARC.

A CNAME record is an alias, and it does not refer to an SPF record.
The CNAME redirects the name *.tug.org (including _dmarc.tug.org) to
tug.org . 
Since TUG has SPF set up, there is a TXT record at tug.org containing
SPF information. There could be many other TXT records at tug.org, as
well as A, MX and other records.
Hence a query for TXT records at _dmarc.tug.org returns the
information that there is an SPF TXT record at tug.org . It does not
return any DMARC TXT record, either at _dmarc.tug.org or at tug.org .
Thus DMARC correctly concludes that tug.org does not have DMARC set
up.

Having just checked the DMARC wiki, I find that CNAMEs are expected to
be followed when looking up DMARC records.

So now tug.org could do two thing to deploy DMARC - it could attach a
DMARC TXT record to tug.org, in which case lookup for _dmarc.tug.org
wil find that via the CNAME; or it could - correctly - put the DMARC
record at _dmarc.tug.org, in which case lookup for _dmarc.tug.org will
find that record directly, as wildcard CNAMEs are not applied to any
domain for which a real record exists.