On 2023-05-06 at 18:44 +0200, Christian Seitz via mailop wrote:
> If I am not wrong a DNS zone can only have a single SOA record. Yahoo
> requests 
> an SOA record per subdomain. That does not make any sense to me. We
> would have 
> to create one DNS zone per subdomain, but that's not how DNS is
> designed.
> 
> Am I completely wrong? What did I miss? Is this a mistake somebody
> who doesn't 
> know much about DNS defined as a requirement or is this just another
> "we are 
> big so we can request whatever we want and whatever makes your life
> hard" thing?

You could probably do some hackish delegation to get a SOA per
subdomain, but such requirement makes no sense. First, if they really
wanted to restrict email domains they accept to the ones that are
registered, rather than looking for a SOA they should be using the PSL,
where in-berlin.de has been for years [1]. And second, such policy
would still be broken. While email addresses _generally_ use the
primary domain, email addresses not on a second level domain have been
used for as long as there have been subdomains. RFC 5321 itself
contains an example of that, although references to such usage can be
found many years back (e.g. RFC 974).
It is relatively common to find that pattern of "subdomain emails" in
Universities, with email domains linked to the different departments.
It is also very common to have "alumni emails" that use a subdomain of
the main university domain [2,3,4,5]

None of those would now be able to email yahoo accounts, apparently. I
find it hard to believe that they may have added such restriction on
purpose. It may be that a check inadvertently added a dependency on th
domain part of the email address having a SOA record. Or even that
their statement that they now require a SOA was actually wrong and your
issue slightly different.

There are several Yahoo people on the list. I'm sure they will
investigate what's really going on.


Regards



1- https://github.com/publicsuffix/list/pull/711
2- https://alumni.stanford.edu/perks/email/
3- https://alumniemail.ud.purdue.edu/
4- https://www.alumni.columbia.edu/content/alumni-email
5- 
https://www.thecrimson.com/article/2023/5/5/haa-retains-alumni-emails/


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