Can´t send to one specific domain (mailserver actually)

[DrBaltar]

I´ve been struggling with this situation for days and can´t find a solution, or even a motive...

On Exchange 2000 Server SP3 we are having problems sending mail to one specific mailserver.
Sending mail to any other domain is not causing any problems.
Receiving from this domain seems to work.

They claim to have the issue just with us, and we are sending w/o problems to anyone but them.

In fact, the issue seems to be not with the domain but with the mailserver.
The mailserver belongs to an ISP who hosts and administers email for two companies with differnet domains to whom we are unable to send.

The recipient´s ISP (who admins the mailserver) is basically ignoring the issue and the requests from me and the other company (their own client!).

* None of the domains/IPs is blacklisted.
* We are NOT filtering them and they are supposedly not filtering us.
* Traceroutes to their mailserver seem to get stuck at a firewall at the border of the ISP netwwrk.
* DNS and revDNS resolution look fine from both ends.

--- ERROR Codes ---
I don´t know if any error is being logged/reported at the other end.
I found no error in our smtp log.
These are the error codes I do get while testing:

- NDR
Sent mails are finally bounced with an NDR.
The reported error code is 4.4.7, wich by MS KB is this:

Numeric Code: 4.4.7
Possible Cause: The message in the queue has expired. The sending server tried to relay or deliver the message, but the action was not completed before the message expiration time occurred. This NDR may also indicate that a message header limit has been reached on a remote server or that some other protocol timeout occurred during communication with the remote server.
Troubleshooting: This code typically indicates an issue on the receiving server. Verify the validity of the recipient address, and verify that the receiving server is configured to receive messages correctly. You may have to reduce the number of recipients in the header of the message for the host that you are receiving this NDR from. If you resend the message, it is placed in the queue again. If the receiving server is on line, the message is delivered.

- TELNET
When trying to telnet to their smtp I get inconsistent behavior from the recipient´s server,
The few times when a session is established, my "mail from:" command is rejected with a "501 could not parse your mail from command".
Most of the time it just timesout.

I am testing from two different locations and ISP.
-

I believe the problem is at their end, but I would like to at least comfirm it in any way.
Any help will be greatly appreciated.

TIA.

 

[Smorgan11]

not on similar Ip range as you are they? you dont use the same ISP as them?

 

[DrBaltar]

Nope, not similar IP range or ISP.
Also, I mentioned that a second domain in their ISP was not getting our mails, but it _seems_ that one was a false alarm.

 

[nickpark]

Are you using mail from: correctly. ie:
mail from:<user@domain.com>
(including the < and > symbols as these are required)

However, it looks like the connection timeout is the issue. Tried from a different server/ip address?

 

[paulha]

Do you have reverse DNS configured ?

Check it at dnsreport.com

 

[nickpark]

Also, are you really dr baltar, ruler of the colonies?

 

[DrBaltar]

>>> Are you using mail from:
[...]However, it looks like the connection timeout is the issue. Tried from a different server/ip address?

Works ok from a couple other IPs, and I can´t get even there from our IP.
By now I am convinced they have blocked us at some point and are doing nothing to pin-point the issue.

>>> Do you have reverse DNS configured ?

It was missign, but created a couple of weeks ago. thing didn´t improve though.

>>> Also, are you really dr baltar, ruler of the colonies?

Let´s put it this way shall we?... There is a cute blond I need to mail at New Caprica, so you get an idea of how important this actually is.

 

[Spirit]

Not changed your ip recently I've seen mail servers forget to update their cache so when the do a reverse look up they see the old address so reject the mail.

(on their server)

Iain

 

[DrBaltar]

The admin at the other end reacted after I issued a formal complain and we did some test and compared results.

We are both stuck now...

and the whole issue -apparently- can be summarized like this:

* It is not possible to establish a communication from our IP to their smtp.
* This happens with all of the domains using that mail server.
* This does not happen if I do a telnet test from a different ISP.
* I get no error message during the attempt, the other admin claims they don´t get errors logged either, but I can´t be certain they are really looking at the logs.
* All of the admins involved claim they have no blocks/filters that should be causing this.
* The server´s admin in question tough, can´t explain why I can not telnet to their smtp only from my IP.

Is there any way I can trace the connection and find for certain where it fails or gets dropped/blocked ?

I would really appreciate any ideas.

Thanks.

 

[rmcdaniel]

I've just gone through a similar issue. Turns out I have three domains who are using the same isp/email host to handle all their email routing. The host (TimeWarner/RoadRunner) was blocking me. I was able to use dnsstuff.com to figure out through their email lookup the name of their mail server then I tried telnetting into their mail servers which gave me a mail rejected error. We were blacklisted quite awhile ago and Road Runner just didnt update their cache after the blacklisting was cleared. So it still sounds like they are blocking you through theri isp/mail host they just dont know it. I wound up having to go to Road Runner for removal requests.

Hope this helps