On Thu, 25 Apr 2024, Paul Menzel via mailop wrote:
Until now we rejected emails from donotre...@invoices.premierinn.de
2024-04-23.log:2024-04-23 17:48:53 194.95.238.12 <22>Apr 23
17:48:53 mgw6-erl postfix/smtpd[744016]: NOQUEUE: reject: RCPT from
fra-smtp2.oracleindustry.com[138.1.67.161]:19102: 554 5.1.8
<donotre...@invoices.premierinn.de>: Sender address rejected: Domain
not found; from=<donotre...@invoices.premierinn.de>
to=<u...@molgen.mpg.de> proto=ESMTP
helo=<fra-smtp2.oracleindustry.com>
because the return path would not work.
$ host invoices.premierinn.de
$
On 25.04.24 14:59, Andrew C Aitchison via mailop wrote:
Should someone here not know, RFC 7505
A "Null MX" No Service Resource Record for Domains That Accept No Mail
is the accepted standard way to signal a domain that does not receive email.
This is not a null MX. Null MX doex explicitly exist and points to ".".
invoices.premierinn.de has no A, AAAA or MX records.
null MX would look like:
invoices.premierinn.de. 1800 IN MX 0 .
The domainonly has SPF record which is a bit strange, but from the mail
point of view it does not exist.
invoices.premierinn.de. 1800 IN TXT "v=spf1 include:oracleindustry.com
~all"
So, there is no reason to accept mail from/to invoices.premierinn.de.
By using the MX records suggested there, a recipient would know
that the sender acknowledges sending mail from that domain.
It's the opposite. Null MX is designed to know a host does not send/receive
mail, so you don't accept mail from/to such host.
I would personally prefer if the MX records started being explicitly required
- so we don't expect all host with A/AAAA records to accept/send mail and
don't need to mark them with Null MX to say "no we don't"
but changing this is for long run.
--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
Microsoft dick is soft to do no harm
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