On 2026-02-15 at 11:24:39 UTC-0500 (Sun, 15 Feb 2026 17:24:39 +0100)
lejeczek via Postfix-users <[email protected]>
is rumored to have said:
Hi guys.
I won't ask is that possible - though certainly it made me frown -
because it's happening.
Everywhere - so far - I emailed, including usual suspects, eg.: gmail,
yahoo, etc. I got _pass_
Now I get bounces - only from this one place/destination - saying:
This is an authentication failure report for an email message received
from IP
xx.yy.zz.aa on Sun, 15 Feb 2026 09:05:58 -0600 (CST).
Feedback-Type: auth-failure
Version: 1
User-Agent: OpenDMARC-Filter/1.4.2
Auth-Failure: dmarc
Authentication-Results: mail.some.net; dmarc=fail
header.from=MY.domain
...
dkim=fail reason="signature verification failed" (1024-bit key)
header.d=MY.domain [email protected] header.b=EFnQn
...
and I only wonder - could it be not me but someone in "between"?
Theoretically, yes. In a sense, it is almost certain to be something in
between you and whoever is failing the message, as you know that you
generate messages that are NOT broken. ALL mailing lists which make body
modifications (like the footer on this message) will break the original
body hash signature. Some mailing list software (such as Mailman3, which
manages this list) fixes this by changing the From header and re-signing
the message. Getting mailing list software to do the right things in all
cases can be tricky. Some list owners just don't bother.
That IP I "obfuscated", is not mine.
This a popular, I think, mailing list and since I'd like to be able to
mail to them, I wonder - in case it's me - if there is anything I can
do.
Obfuscating the address and the specific domains involved makes it
impossible for us to explain the problem in anything more than
theoretical terms. Many of us run mail systems and may have direct
experience with the particular systems involved.
--
Bill Cole
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