Re: yahoo and "bulk" folder

["Jim Franz" <franz400@xxxxxxxxxxxx>]

I knew someone could turn my rambling into dns-speak...

Ken - would you consider sharing exactly how you achieve such spam blocking 
perfection??

jim franz

----- Original Message ----- 
From: "Ken Sims" <mdrg5003@xxxxxxxxxxx>
To: "PC Technical Discussion for iSeries Users" <pctech@xxxxxxxxxxxx>
Sent: Thursday, July 27, 2006 4:31 PM
Subject: Re: [PCTECH] yahoo and "bulk" folder


> Hi Dan -
>
> > I'm curious, how does a DNS not get set up correctly?
>
> To give you essentially what Jim said, but from a slightly different 
> angle:
>
> The IP address of the sending mail server needs to have reverse DNS (a PTR
> record) which gives a fully qualified host name.
>
> That fully qualified host name needs to have a regular DNS entries which
> gives back one or more IP addresses, of which one IP address is where you
> started.
>
> The reverse DNS host name does NOT have to match the mail server's primary
> name.
>
> A real life example:
>
> My mail server's primary name is mail.kensims.net.  That's how it
> identifies itself in the EHLO command when it connects to another mail 
> server.
> mail.kensims.net resolves to 24.234.149.199 and 65.40.146.221.
>
> Most of my outgoing mail I relay through smart hosts.  Unrelayed mail
> always goes out through IP address 24.234.149.199.
>
> 24.234.149.199 has reverse DNS c.kensims.net (not mail.kensims.net).
> c.kensims.net resolves to 24.234.149.199 only.
>
> If 24.234.149.199 did not have a reverse DNS entry, that would be a
> problem.  Or if it had a reverse DNS entry but that host did not resolve
> back to 24.234.149.199, that would be a problem.
>
> Personally I do not reject email based on missing or incorrect DNS of any
> kind.  I do reject on a lot of other things, but that's a whole different
> topic.  Let me just say that the last piece of spam that actually made it
> on to my server was on 18-Dec-2005, and that's without any content
> filtering or the use of any external blocklists or any other external 
> services.
>
> Ken
> http://www.kensims.net/