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Re: [tlug] [slightly OT] SMTP and the internet, protocols and the internet

On Mon, Jan 11, 2021 at 02:43:08PM +0100, Christian Horn wrote:
> On Mon, Jan 11, 2021 at 12:24:07PM +0000, Schwartz, Fernando G. | @SCA wrote:
> > 
> > Further, if you check at < >,
> > 
> > 220 ESMTP Postfix (Debian/GNU) is missing a " rDNS " to the IP.
> > That's probably the main issue.

Hm.. the tool says "Reverse DNS is not a Valid Hostname", but no

I thought I had seen an issue, but it looks ok to me.
I had seen 'dig -x' returning 'fc' instead of
'', turns out that is a "feature" of 

Since Fedora33 it is default.  I have
in /etc/resolv.conf, and requests like done with 'dig' are 
running through systemd-resolved.  The "feature" is that it
used an entry like fc
in /etc/hosts to return then "fc".. interesting.
But I'm not sure what they think how rDNS should be broken.

t-online was also seein rDNS in order, that was not the
issue leading to rejecting the mails.


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