[GRLUG] Postfix HELO issue

[Grand Rapids Linux Users Group]

Ok, I thought you had solved it and were merely commenting.

The problem is that whatever is trying to send, is connecting and sending
just

"HELO majordomo"

instead of using its full FQDN, eg

"HELO majordomo.DOMAIN.COM"

The receiver is requiring a full hostname with domain be in the HELO.

Either you need to adjust what your sender (Majordomo, I assume) software
to use the full hostname, or (if you control the server it is sending to)
adjust its configuration to not require a full host name either generally,
or specifically from that sender host.


On Thu, Aug 5, 2021 at 3:50 PM Grand Rapids Linux Users Group <
grlug at grlug.org> wrote:

> On Thu, 5 Aug 2021, Grand Rapids Linux Users Group wrote:
>
> > Yes, many, but not all, SMTP servers require a fully valid hostname, with
> > domain, in the HELO.
> >
> The subdomain is valid (MX, DKIM, DMARC all validate), .. and reverse DNS
> matches the full hostname:
>
> $ host majordomo.mailman.dd.org
> majordomo.mailman.dd.org has address 24.38.nn.134
>
> ; <<>> DiG 9.16.6 <<>> -x 24.38.dd.134
>
> ;; QUESTION SECTION:
> ;134.dd.38.24.in-addr.arpa.     IN      PTR
>
> ;; ANSWER SECTION:
> 134.dd.38.24.in-addr.arpa. 86400 IN     PTR
> majordomo.mailman.dd.org.
>
> > Often then will do a lookup on it in DNS to make sure it is real/exists
> as
> > well. Some even insist that the IP they get match the IP that the SMTP
> > connection is from.
> >
> Any thought on how to determine if is actually a subdomain problem?
>
>         Thanks!!
> --
> grlug mailing list
> grlug at grlug.org
> https://shinobu.grlug.org/mailman/listinfo/grlug
>
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