Re: email lacks sender address
On Thu, Apr 28, 2022 at 12:02:50PM -0500, David Wright wrote:
> $ cat /etc/mailname
> acer.corp1
> $ cat /etc/hosts
> 127.0.0.1 localhost
> 127.0.1.1 acer1.corp acer1
> 192.168.1.14 axis.corp axis
>
> # The following lines are desirable for IPv6 capable hosts
> ::1 localhost ip6-localhost ip6-loopback
> ff02::1 ip6-allnodes
> ff02::2 ip6-allrouters
> $ hostname
> acer
But you no longer have 'acer' in your /etc/hosts file. Your hostname
therefore won't have *any* canonical form with dots in it.
> $ domainname
> (none)
That's an NIS command. It's used by NIS only. It has nothing to do
with what you appear to think a "domain name" is.
> and here's the email on axis:
>
> >From auser@acer.corp Thu Apr 28 11:37:06 2022
> Return-path: <auser@acer.corp>
> Envelope-to: auser@axis
> Delivery-date: Thu, 28 Apr 2022 11:37:06 -0500
> Received: from [192.168.1.10] (helo=acer)
> by axis.corp with esmtp (Exim 4.92)
> (envelope-from <auser@acer.corp>)
> id 1nk78c-0001yL-Bm
> for auser@axis; Thu, 28 Apr 2022 11:37:06 -0500
> Received: from auser by acer with local (Exim 4.94.2)
> (envelope-from <auser@acer>)
> id 1nk78b-0000HX-6v
> for auser@axis; Thu, 28 Apr 2022 11:37:05 -0500
Here, you can see that there was no canonical expansion of "acer" into
a dot-laden name, so your system only identified itself as "acer". Not
as "acer.corp" or anything similar, in its HELO.
If one of the entries in your /etc/hosts file had contained "acer" as
an alias, then the outcome would have been different.
Interestingly, acer.corp *does* appear in the envelope sender address,
which you can see in the "From " line and the "Return-path:" header.
But in the bottom Received: header, it says "envelope-from <auser@acer>".
I find that quite interesting, but you'd need more knowledge of exim
configuration than I possess to work out what happened there.
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