Just want to make sure this is what you think it is...
On Sun, 14 Jun 2026, Al via Postfix-users wrote:
[...]
I keep getting disabled on [email protected] mailing list. I
have resubscribed many times.
I presume you actually queried the list manager to verify your
subscription or lack thereof...
Is there a problem with my configuration?
What can I do to fix this?
You need to stop rejecting mail from the list. That could be because
you've chose strict DMARC enforcement, which is incompatible with most
discussion mailing lists.
I am not using DMARC.
That makes the situation less obvious.
;-)
Examine your logs to find the
rejections, which should give you a hint as to why they are happening.
I have taken a look at my logs:
This is the error:
Jun 9 12:03:41 sequoia postfix/smtpd[52759]: NOQUEUE: reject: RCPT from
unknown[45.90.5.195]: 554 5.7.1 Client host rejected: cannot find your
reverse hostname, [45.90.5.195]; from=<[email protected]>
to=<[email protected]> proto=ESMTP helo=<list.sys4.de>
However, most of the of the time it lets, it through:
0.43, dsn=2.6.0, status=sent (250 2.6.0 <[email protected]> Message accepted
for delivery)
Jun 14 06:35:36 sequoia postfix/qmgr[83260]: 4DC2D1F5A07: removed
45.90.5.195 is list.sys4.de:
# dig -x 45.90.5.195 +short
list.sys4.de.
It actually says this in the log message you posted:
helo=<list.sys4.de>
From this I skull that
1) you are checking the reverse lookup and rejecting mail where the
result doesn't match what was announced with HELO; and
2) reverse lookups are failing
Where the reverse lookup is failing, I don't know.
This is probably a good time to ask: do you run a local caching DNS server
alongside postfix (or within a couple of hops)? Aside from the Other
Important Reasons, if you're not running it locally then you're not going
to have logs to refer to; you might try tcpdump, but if it's a sporadic
problem it might be a quiet day fishing.
--
Fred Morris, internet plumber
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