Opinion needed on mail delivery failure error.

[mzenzer]

First the details. I have Exchange 2003 SP1 installed on a Windows 2003 SBS Premium machine. SBS is patched to the latest available. I am running CA Etrust Secure Content Manager for SPAM and virus scanning on incoming emails. This application is also patched to the latest available.

Now on to the problem. Emails will bounce when sent from a location that uses the same ISP as the location of the Exchange Server, i.e., Eatel (again, which is the ISP).
ALL emails from locations not served by Eatel, can send mail successfully to the Exchange Server in question.

One of the locations that CANNOT send mail to the server in question is my office. When I send a message I get the following error:

The original message was received at Thu, 7 Oct 2004 16:39:33 -0500 (CDT)
from XXXX.eatel.net [209.124.XXX.XX]

----- The following addresses had permanent fatal errors -----
<zenzer@XXXXXXXXX.com>
(reason: 550 Host unknown)

----- Transcript of session follows -----
550 5.1.2 <zenzer@XXXXXXXX.com>... Host unknown (Name server: 64.237.XX.XX: host not found)


If I send a message from a system that uses a different ISP, and I've used about half a dozen to test this, email goes through perfectly.

In fact, when I'm at home, and NOT on an Eatel network, I can send mail to the Exchange server in question using the same account I do from my office, but with my ISP's SMTP address, email works perfectly.

I have completely disabled Etrust and still get the same results.

The server that bounces back the message is always XXXX.eatel.net [209.124.XXX.XX].

Also, its not just the account in my sample bounce above. I have tried this with several accounts, accounts which are having no problems receiving mail otherwise, and still get the same message. In other words, other accounts on the Exchange server.

My point of all this is that the ISP is blaming me. They say that, and I quote, "DNS at address 64.237.XX.XX is not accepting messages from Eatel". WTF are they talking about? 64.237.XX.XX is the address of a Cisco PIX, which forwards SMTP messages to the Exchange server. The only DNS involved is a typical setup on a single AD domain, with local DNS configured to forward to the net when needed.

What I would like to know is if anyone thinks the ISP is correct? Is it something on my end, or is it something in their system?

Personally, I think something with their DNS is the problem.

Thanks for your time,

Mike

 

[snootalope]

Mike, couple of questions.. Sorry if these are stupid questions but i've read your post a dozen times and i'm a little confuzed..

1. Can your Exchange server recieve any inbound messages from any domain?

2. "Emails will bounce when sent from a location that uses the same ISP as the location of the Exchange Server, i.e., Eatel (again, which is the ISP)."

That really confuses me.. So the Excahnge server is at your ISP?? Could you lay out the path an email would take coming to you from like hotmail or something??

To me, it sounds like you've got an internal DNS problem. Don't get mad at me, it's just a guess! If the ISP had a DNS problem, believe me, they'd be having a hell of a lot more problems than one client not being able to send email..

Do you have an internal domain setup? Like using Active Directory or anything? What about an internal DNS server. Obviously you've gotta have somekind of dns routing on your exchange server, so how do you have that setup exactly? Is your exchange server your internals DNS server?

just a little more internal detail would be very helpful..

-snoots

 

[mzenzer]

1. Yes, the Exchange server receives messages just fine from any other domain (ISP) except Eatel.

2. No, the Exchange server is in an office, which has an Eatel T1 line. MY office, which is geographically miles away, in other words has no connection to the domain containing the Exchange server.

However, at my office we also use Eatel as our ISP. As do other people associated with the company running the Exchange server. None of us can send to the Exchange server. Again, that is from an Eatel line.

The problem occurs whenever outgoing mail from a remote location is routed through 209.124.XXX.XX. It never makes it to the exchange server.


Hope this helps, and thanks for the response!

 

[Marcs41]

A check: did you try to Telnet that server?
By name AND by IP.
If it works by IP and not by name, there is indeed a DNS issue .. somewhere.
You can also check with tracert, smae thing, IP and Name.
If it doesn't work with the name...DNS

Marc
_{If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC!
How Do You Get Great Answers To my Tek-Tips Questions?} See faq222-2244

 

[mzenzer]

Yes, I can telnet to port 25 both by name and IP.

The server works flawlessly in all other aspects. I've checked and re-checked my DNS, and had another tech from my company look it over as well. I've cleared the DNS cache, flushed it, everything.

 

[mzenzer]

Also, I did these telnet tests from the location that is having trouble sending mail to the exchange server. If I use an SMTP (such as that built into XP) bypassing Eatel's SMTP server, then mail goes through fine.

However, If I use Eatel's SMTP, the mails are rejected by their server, as stated above.

 

[Marcs41]

In your first post you say:

They say that, and I quote, "DNS at address 64.237.XX.XX is not accepting messages from Eatel

Do you have any means to check their claim?
In other words, can you get to that location and get some logs that would reject traffic from them, better yet, can you see it come in at all?
If you can see it gets in, but rejected, there may indeed be an issue at that location.
If they don't even come in, have Eatel PROVE their claim.

Marc
_{If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC!
How Do You Get Great Answers To my Tek-Tips Questions?} See faq222-2244

 

[mzenzer]

Nope, I don't see them come in at all.

 

[Marcs41]

In that case, see last line previous post.
We cannot check that for you.

Marc
_{If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC!
How Do You Get Great Answers To my Tek-Tips Questions?} See faq222-2244