Reverse DNS

Reverse DNS

[Peter H.]

Hi,

Since I have a broadband Internet connection I cannot send mail any longer to 
addresse of @aol.com. An account that:

Reverse DNS lookup for your IP address is failing. AOL does require that all 
connecting Mail Transfer Agents have established reverse DNS.

After that message I went to reverse DNS research tool where I entered the IP 
address of the braoadband provider and the result is:

Quote
Success! It appears you have Reverse DNS. Please note the following points:

     * If the sender's domain is the only domain sending mail from a specific 
IP address, we recommend that the reverse DNS entry (PTR Record) match the 
domain name (A Record), but we do not require it.

     * AOL does require that all connecting Mail Transfer Agents have 
established reverse DNS, regardless of whether it matches the domain.

    *  Reverse DNS must be in the form of a fully-qualified domain name 
-reverse DNSes containing in-addr.arpa are not acceptable, as these are merely 
placeholders for a valid PTR record. Reverse DNSes consisting only of IP 
addresses are also not acceptable, as they do not correctly establish the 
relationship between domain and IP address.
Unquote

I do not have an e-mail address with the broadband provider instead continue 
using the same current address of my ISP when I had only a modem connection.

On the web page http://postmaster.info.aol.com/errors/421dnsnr.html it says 
among others:

Quote
If you are on a dynamic IP address, please call your ISP and request a static 
IP address with proper rDNS before attempting to send mail to AOL through that 
server.
Unquote

The problem is I have no telephone nor my neighbors for the past 2 months. The 
telephone company apparently blew-up a connection box and has been so far 
unable to repair it.

Any suggestions how to go about it and where do I put the reverse DNS of my 
e-mail provider if I ever will get it.

In the meantime I am sending mail to @aol via operamail.

Thanks & regards 
-- 
Peter

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Re: Reverse DNS

[Ray Olszewski]

Peter H. wrote:
> Hi,
> 
> Since I have a broadband Internet connection I cannot send mail any longer to 
> addresse of @aol.com. An account that:
> 
> Reverse DNS lookup for your IP address is failing. AOL does require that all 
> connecting Mail Transfer Agents have established reverse DNS.
> 
> After that message I went to reverse DNS research tool where I entered the IP 
> address of the braoadband provider and the result is:
> 
> Quote
> Success! It appears you have Reverse DNS. Please note the following points:
> 
>      * If the sender's domain is the only domain sending mail from a specific 
> IP address, we recommend that the reverse DNS entry (PTR Record) match the 
> domain name (A Record), but we do not require it.
> 
>      * AOL does require that all connecting Mail Transfer Agents have 
> established reverse DNS, regardless of whether it matches the domain.
> 
>     *  Reverse DNS must be in the form of a fully-qualified domain name 
> -reverse DNSes containing in-addr.arpa are not acceptable, as these are merely 
> placeholders for a valid PTR record. Reverse DNSes consisting only of IP 
> addresses are also not acceptable, as they do not correctly establish the 
> relationship between domain and IP address.
> Unquote
> 
> I do not have an e-mail address with the broadband provider instead continue 
> using the same current address of my ISP when I had only a modem connection.
> 
> On the web page http://postmaster.info.aol.com/errors/421dnsnr.html it says 
> among others:
> 
> Quote
> If you are on a dynamic IP address, please call your ISP and request a static 
> IP address with proper rDNS before attempting to send mail to AOL through that 
> server.
> Unquote
> 
> The problem is I have no telephone nor my neighbors for the past 2 months. The 
> telephone company apparently blew-up a connection box and has been so far 
> unable to repair it.
> 
> Any suggestions how to go about it and where do I put the reverse DNS of my 
> e-mail provider if I ever will get it.
> 
> In the meantime I am sending mail to @aol via operamail.
> 
> Thanks & regards 

We could perhaps help more if we had the missing details.

1. What e-mail address is involved in the problem? For now, I'm going to 
guess that it is <heisspf@skyinet.net>.

2. AOL says you don't have reverse DNS; some unidentified "reverse DNS 
research tool" says you do. Let's see ...

	ray@kuryakin:~$ host skyinet.net
	skyinet.net             A       202.78.97.2
	ray@kuryakin:~$ host 202.78.97.2
	Name: ns.skyinet.net
	Address: 202.78.97.2

	ray@kuryakin:~$ host ns.skyinet.net
	ns.skyinet.net          A       202.78.97.2

This looks good. It is how reverse-DNS is supposed to look.

3. But perhaps the problem is that you are not actually sending your 
mail from the above IP address? Looking at the headers for the message 
you sent here, it came from an MTA at 203.87.189.146 . Let's look at 
that address ...

	ray@kuryakin:~$ host 203.87.189.146
	203.87.189.146 does not exist, try again

So there is the problem; the *actual* IP address of your broadband 
connection lacks a reverse-DNS entry.

What to do about this? I'm afraid the advice you found to complain to 
your ISP is right. Reverse-DNS entries need to be provided by whoever is 
authoritative for the *address*, not the domain name, and that (almost 
without exception, for us small users) is your ISP. This lookup failure 
suggests a degree of sloppiness at your ISP that would have me looking 
elsewhere for a service provider.

How to contact your ISP really is not a Linux issue, except perhaps to 
point out that VoIP options exist for use with Linux, if your lack of a 
wireline phone really is a persistent problem.

In the meantime -- does your ISP provide a mail forwarder? Most do. If 
so, setting up your MTA to send mail through that forwarder would 
probably satisfy AOL's requirements.




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Re: Reverse DNS

[Ray Olszewski]

I added the mailing list back in with this reply.

Peter wrote:
> ray@comarre.com said:
> 
>>3. But perhaps the problem is that you are not actually sending your  mail
>>from the above IP address? Looking at the headers for the message  you sent
>>here, it came from an MTA at 203.87.189.146 . Let's look at that address ...
> 
> 
>>	ray@kuryakin:~$ host 203.87.189.146
>>	203.87.189.146 does not exist, try again
> 
> 
>>So there is the problem; the *actual* IP address of your broadband
>>connection lacks a reverse-DNS entry.
> 
> 
> Yes I send the mail via the broadband ISP. Now, cat /etc/resolv.conf I get:
> 
> nameserver 203.87.128.3
> search meridiantelekoms.com
> 
> then I get:
> 
> heisspf@~:$ host 203.87.128.3
> 3.128.87.203.in-addr.arpa domain name pointer dns1.meridiantelekoms.com.
> 
> heisspf@~:$ host dns1.meridiantelekoms.com
> dns1.meridiantelekoms.com has address 203.87.128.3
> 
> So there is a reverse DNS.

Foe the nameserver there is, but that is irrelevent to your problem.
> 
> Where does that "actual" ISP 203.87.189.146 in my mail then come from?
> 

Every e-mail has, in addition to the headers you see (like To: and 
From:), a bunch of other headers that most MUAs do not display. In 
particular, there will be a series of Received: headers that report the 
path of SMTP relays that the message took to get from the sender to the 
recipient. All MUAs I've used offer the option of displaying these 
headers, but there is really no standard for how to do that, so I cannot 
tell you how your MUA (whatever it is) can be set to show them.

In the case of the message you sent to me, it contained this final 
Received: header --

Received: from [203.87.189.146] (helo=skyinet.net)	by celine.comarre.com 
with esmtp (Exim 3.35 #1 (Debian))	id 1DXrdx-0004FF-00	for 
<ray@comarre.com>; Mon, 16 May 20

This tells me that your MTA runs on a machine that appears to the 
Internet to have the IP address 203.87.189.146 ... whether it itself has 
that address or is behind a router that SNATs it to that address is 
something I cannot determine. But for the AOL purposes, it does not 
matter. What matters is that when you send a messge to someone@aol.com, 
the AOL MTA sees the message as coming from an MTA at 203.87.189.146 and 
tries to reverse-lookup that address ... which, as I indicated before, I 
cannot do, so AOL probably cannot do it either.

> ray@comarre.com said:
> 
>>This lookup failure  suggests a degree of sloppiness at your ISP that would
>>have me looking  elsewhere for a service provider.
> 
> 
> Meridiantelekoms has set-up and operates the broadband connection, therefore, 
> I can't possibly change them. In the meantime I have informed them of the 
> problem.

At least here in the USA, most communities have more than one broadband 
supplier. Were I to face your problem, I would at least consider 
changing who I got my broadband service from ... especially if requests 
to fix the problem were ignored.

> ray@comarre.com said:
> 
>>In the meantime -- does your ISP provide a mail forwarder? Most do. If  so,
>>setting up your MTA to send mail through that forwarder would  probably
>>satisfy AOL's requirements.
> 
> 
> As I said skyinet.net my former ISP delivered mail to AOL properly via the 
> modem connection. Now I am still sending and receiving mail using skyinet 
> through meridaintelekoms. Therefore I conclude meridian acts as a mail 
> forwarder. Would that need a special setting-up?
> 
> Thanks & regards

A mail forwarder is an MTA that your MTA uses to send all messages. That 
is, you set it up to send all outgoing mail to (for example) 
mail.myisp.com . For this to work, mail.myisp.com needs to know that it 
is supposed to forward (relay) messages for you, and the details of how, 
even whether, you can use it that way are entirely under the control of 
your ISP.

I do recall your mentioning previously (some months back) that you were 
somehow using skyinet through your broadband connection, but if you ever 
told us the details, I've forgotten them. Do note that if the message 
you sent to me is an example of what you are referring to, it doesn't 
really use skyinet to send the mail ... your on-LAN MTA is sending the 
mail directing to the destination MTA, but is just displaying 
<heisspf@skyinet.net> as the From: address. That approach won't solve 
your AOL problem.

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Re: Reverse DNS

[Nathan Clayton]

On Mon, 2005-05-16 at 08:14 -0700, Ray Olszewski wrote:
> What to do about this? I'm afraid the advice you found to complain to 
> your ISP is right. Reverse-DNS entries need to be provided by whoever is 
> authoritative for the *address*, not the domain name, and that (almost 
> without exception, for us small users) is your ISP. This lookup failure 
> suggests a degree of sloppiness at your ISP that would have me looking 
> elsewhere for a service provider.
> 
> How to contact your ISP really is not a Linux issue, except perhaps to 
> point out that VoIP options exist for use with Linux, if your lack of a 
> wireline phone really is a persistent problem.
> 
> In the meantime -- does your ISP provide a mail forwarder? Most do. If 
> so, setting up your MTA to send mail through that forwarder would 
> probably satisfy AOL's requirements.

A lot of ISPs do this now. They force you to go through their SMTP
server. It helps cut down on spammers using their networks. Quite
frankly, I'm surprised that they even left that port open for you to
send out email on. You could also try using something like dyndns to get
a dynamic DNS name pointing to your IP address.

Change your email client/sendmail/postfix to use the SMTP server that
your broadband provider provides and you should have no problems (you
can usually keep the from and reply-to headers pointing to your other
email address without a problem).

nathan

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Re: Reverse DNS

[Peter]

heisspf@skyinet.net said:
> Since I have a broadband Internet connection I cannot send mail any longer to
>  addresses of @aol.com. An account that:

> Reverse DNS lookup for your IP address is failing.


Thanks to your advise Ray, I complained by to the Broadband Provider and they 
did fix it.

Before:
host 203.87.189.146
203.87.189.146 does not exist, try again

Now:

host 203.87.189.146
146.189.87.203.in-addr.arpa domain name pointer consvictoria-projg.meridian.ph.
189.87.203.in-addr.arpa.

and the mail to aol.com does not bounce any more.

ray@comarre.com said:
> At least here in the USA, most communities have more than one broadband
> supplier. Were I to face your problem, I would at least consider  changing
> who I got my broadband service from ... especially if requests  to fix the
> problem were ignored.

No in my world we have no choice. Even w/o reverse DNS I am thankful that 
somebody provides me with a BB.

Regards
-- 
Peter

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