Re: RES: RES: Email oddity

[Ken Sims <mdrg8066@xxxxxxxxxxx>]

Hi John -

On Fri, 13 May 2011 21:38:22 -0500, jmmckee <jmmckee@xxxxxxxxxxxxxx>
wrote:

> All I did was remove IP address and some domain info.  I don't understand your meaning.  All that was there between the brackets was the IP.  Now, >maybe< what Dennis referenced earlier about DNS changes may be the entire issue, and it gets magically fixed in a few more hours, if not already.  Just checked, and still unknown.

It depends on the specific mail server software, but typically the
first part of the Received: line looks like this:

Received: from mail.kensims.net (c.kensims.net [24.234.189.130]) by

where mail.kensims.net is what my server HELO/ELHOed with and
c.kensims.net is the reverse DNS host name for IP address
24.234.189.130.

As has already been discussed by others, there are legitimate reasons
for the HELO/EHLO host name and the rDNS host name to not be the same.

However a DNS lookup for the rDNS host name better return the
connecting IP address (and can also return other IP addresses).

A DNS lookup for the HELO/EHLO host name should also return the
connecting IP address (and can also return other IP addresses).

The missing rDNS host name in:

Received: 	from BAXTER.X.X.NET ([X.X.X.X]) by
mail7.wildflower.net

may indicate that mail7.wildflower.net is getting a cached negative
response to the PTR request or that the software isn't putting the
rDNS host name in the record.

Ken
Opinions expressed are my own and do not necessarily represent the views 
of my employer or anyone in their right mind.