RE: [Nolug] running a mail server with a Cox account

Hi Scott.

I'm sorry. I reread your message again and I found that I overlooked
something. I have no idea at all what requirements AOL has to forward mail
(from an inside user to the Internet).

On the other hand, if you are talking about their requirements for receiving
mail for one of their own users then they definitely do not require that the
forward lookup match the reverse lookup (for the forward lookup's resulting
IP).

Yes, I've read the FAQ you mentioned. The author is dead wrong about this
item. IP addresses and machine names are not a one-to-one relationship.
>From the FAQ:

>>> Looking up an Internet machine's name should show its correct number,
and looking up the number should show that original name. This is what is
called "reverse DNS".

Looking up a name should indeed show its correct IP. Looking up the IP
should show ONE of the correct names. Looking up THIS name should show the
same IP.

>>> Note that it probably would have been okay for smtp.example.com to
identify itself as barney.example.com. One machine can have many names
assigned to it. The problem comes when a machine is identifying itself as
belonging to two separate domains, which really isn't common or proper in
email headers.

Here he admits that one machine can have many names. Does he think that it
is illegal to use them? What domain each of the names is in has nothing at
all to do with the issue - either two names "match" or they don't (as per
his initial claim).

Want proof? My mail server is "mail.sstar.com". The IP is 209.205.176.7.
A reverse on that IP will yield sr.sstar.com. Neither I nor my users have
any trouble sending mail to AOL users.

So let me review: If you start with an IP and reverse it to a name, then
look up the name, you should get the original IP. But if you start with a
name and look up an IP, then reverse the IP, you are likely to get any name
that the box has. It will always be the same name, but it is up to whoever
sets up the reverse DNS to pick which one. The only test you can perform is
to be sure that there is SOME name when you reverse the IP.

Indeed, some mail servers do this reverse test, but not many. There are FAR
too many faulty DNS setups out there where IP's don't reverse. So ISP's
don't apply this test. That's the real world. The mail must flow! :-)

John

    John Souvestre - Southern Star - (504) 888-3348 - www.sstar.com

-----Original Message-----
From: owner-nolug@joeykelly.net [mailto:owner-nolug@joeykelly.net] On Behalf
Of Scott Harney
Sent: Monday, August 11, 2003 7:11 AM
To: nolug@joeykelly.net
Subject: Re: [Nolug] running a mail server with a Cox account

"John Souvestre" <johns@sstar.com> writes:

AOL is definitely one. And it's been that way for quite a while. Actually
they
require the domain to match and their be a forward lookup if forward does
not
match reverse.

ie. if you call yourself mail.scottharney.com and reverse lookup produce
attitude.scottharney.com, aol will forward the mail if
attitude.scottharney.com
exists. But if you call your mailserver mail.scottharney.com and your
reverse lookup comes back as ipmy-ip-add-ress.no.no.cox.net they'll dump
your
mail silently without error to you or the sender.

http://members.aol.com/adamkb/aol/mailfaq/dropped-mail.html

> Hi Scott.
>
> Yes, for a VERY, VERY few mail servers. But I don't believe that AOL is
> one. From what I learned they do require that reverse DNS produces
> something, but it doesn't have to match the forward lookup.
>
> John
>
> John Souvestre - Southern Star - (504) 888-3348 - www.sstar.com
>
>
> -----Original Message-----
> Probably not necessary since you're relaying through Cox but if you want
> to talk to some mail servers, you need to set up MX records in DNS AND
have
> forward lookup = reverse lookup (AOL does this).
>
>
>
>
> ___________________
> Nolug mailing list
> nolug@nolug.org

-- 
Scott Harney<scotth@scottharney.com>
"...and one script to rule them all."
gpg key fingerprint=7125 0BD3 8EC4 08D7 321D CEE9 F024 7DA6 0BC7 94E5
___________________
Nolug mailing list
nolug@nolug.org
___________________
Nolug mailing list
nolug@nolug.org