On Fri, 24 May 2002, John Horne wrote:
> Hello,
>
> I've noticed a few times that mail I get from our mailhubs have the
> following header line:
>
> Received: from [141.163.66.132] (helo=tracy.csd.plymouth.ac.uk) by
> jhorne.csd.plymouth.ac.uk with esmtp (Exim 4.04) id 17BDZe-000530-00 for
> john@???; Fri, 24 May 2002 12:49:34 +0100
>
> It's the first line that confuses me. My understanding is that my local MTA
> (on jhorne.csd...) is receiving a message from a host with IP address
> 141.163.66.132, and the HELO command says it is 'tracy.csd.plymouth.ac.uk'.
> However, I thought that exim did a reverse lookup of the IP address and
> compared this to the HELO name. If they are the same then the Received:
> header line should look different. I would expect it to look like:
>
> Received: from tracy.csd.plymouth.ac.uk (141.163.66.132) by
>
> My thought is that exim is not getting a DNS reverse lookup for the mailhub
> - if it got anything which didn't match then it would have shown that, but
> it's not showing anything. However, the DNS entry is there and the mailhubs
> local caching name server is well aware of its own name and IP address - I
> ran 'dig' on the mailhub itself.
The mailhub knowing its IP address and name is all well and good. Have
yuor tried to do a lookup from the machine thats _receiving_ the message
from the mailhub - maybe it isnt able to resolve the reverse for the IP.
>
>
> Anyone any thoughts on this? (This is, of course, this weeks 'Friday
> afternoon problem' :-) )
>
>
> Regards,
>
> John.
>
> ------------------------------------------------------------------------
> John Horne, University of Plymouth, UK Tel: +44 (0)1752 233914
> E-mail: jhorne@???
> PGP key available from public key servers
>
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