On Fri, 24 May 2002, John Horne wrote:
> 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'.
Correct.
> However, I thought that exim did a reverse lookup of the IP address and
> compared this to the HELO name.
Exim only does a reverse lookup if its configuration requires it to.
Either because the host matches lookup_hosts, or because something in
the configuration does a test against the host name.
It is, of course, more efficient for lookups not to happen.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
