Re: [Exim] DNS related probs.

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Author: Giuliano Gavazzi
Date:  
To: Exim Users Mailing List
Subject: Re: [Exim] DNS related probs.
At 13:58 -0400 2003/10/22, Greg A. Woods wrote:
>[ On Wednesday, October 22, 2003 at 10:59:58 (+0200), Giuliano
>Gavazzi wrote: ]
>> Subject: [Exim] DNS related probs.
>>
>> I do not agree! I know it's a question of opinion, but id Exim knows
>> that the helo name is genuine as it corresponds to the host address,
>> wouldn't it be better to set the sender_host_name to the
>> sender_helo_name?
>
>I'm not sure exactly what Exim does with sender_host_name and
>sender_helo_name, but if they're used in composing the "Received:"
>header then you don't want to mess with them.

[...]
>    Received: from
>exim-colo-01.whoc.theplanet.co.uk([195.92.249.251] port=50399)

>
>In this case the reverse DNS matches exactly:
>
>    $ host -i 195.92.249.251
>    251.249.92.195.in-addr.arpa     PTR
>exim-colo-01.whoc.theplanet.co.uk

>
>so my mailer did not include the PTR target name in the comment. Had it
>not been the same, and yet was still allowed, then the result might have
>looked a bit like this (manufactured from information in the other
>headers of your posting):
>
>    Received: from
>mailhost.humph.com(dsl-217-155-139-146.zen.co.uk[217.155.139.146]
>port=63730)

>
>So, in other words, if you mess with sender_host_name then you may
>destroy valuable informatoin that should be included in the received
>header!


oh, yes, I absolutely agree with that. But the case I gave was of a
host with two PTR records of which both had the correct A record
(giving back that same host, that is). Now, although not absolutely
essential, since sender_host_name is not a list, it would have been
kind to use the sender_helo_name for sender_host_name, as that, in
this particular case, corresponded to one of the two PTRs. After all
there is no priority in multiple PTR or A records (unless they are
given round robin, but then it is a diffirent kind of fish
altogether).

The workaround I proposed was only for internal use, as it set only
an acl variable, and it would not change the received headers anyway.

Giuliano
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