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Exchange5.5 - Can't send to some domains

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5 replies

by christotg

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I have the following symptoms on my LAN:
Bo cannot send email to Fred@isp.com - Exchange returns an NDR after 2 days stating "the server sould not be contacted"
Denise can send email to Fred@isp.com.

So when Bo needs to send the email, he sendsit to Denise and she sends it. Works fine.

But wait... there's more!

Fred@isp.com cannot send email to Denise.
Fred@isp.com can send email to Bo.

There's still more....

Grant can't send email to Joe@otherisp.com - Exchange NDRs with "Recipient name not recognized".
I can send email to Joe@otherisp.com properly.
Joe@otherisp.com cannot send to Grant. It bounces with an NDR i haven't seen yet.
Jackie can send email to Joe@otherisp.com.
Grant can send email to most accounts @otherisp.com but some, like Joe@otherisp.com, don't go through.

These problems seem to be completely random in nature. Some people cannot send email to some other people or domains, and some external people or domains cannot send email to some internal people. Unfortunately, the problems are permanent and don't go away.

Here is what I've noticed:
DNS is set up properly. The MX record for the office is correct. The Exchange server can resolve MX records properly and I can telnet to the remote mail servers successfully.

I changed the DNS server that the Exchange server points to & rebooted, to no effect.

I built a new server and copied email (not the databases... I exported to .PST & imported to the new server) and had no changes to the problem.

I just bought some black candles and I'm preparing to sacrifice a goat.

If any of you know what might be happening, I'd be very grateful for a pointer or two. Goat blood is hard to get out of carpeting.

5 replies

by christotg

- The server is Small Business Server 4.5 with NT Service Pack 6a and Exchange service pack 4.

- Another way of looking at the problem would be "What could I do to a network to make my symptoms appear?"..

by jayanth

Hi,
Well you problem seems somewhat peculiar. These things sometimes happen if the DNS is not setup properly or name resolution doesnt occur properly. But you say that DNS is able to resolve those problematic domain names. also you are able to telnet to port 25 on those mail servers. This rules out any problem on the DNS issues.

Maybe you can enable the event logging for SMTP and watch any error messages in the event viewer. The error messages and the event id's which you might get, also may help in diagnose the problem.

Also check the NDR's for **all** problematic messages throughly (post them here if you wish to) for any clues you can obtain.

Further make sure that your Internet Link to the local ISP does not have any CRC errors and things like that. If you have a router, then check the CRC errors on the link and contact your ISP for further help, if you see those errors increasing very fast.

by christotg

The problem was traced to a buggy Cisco firewall. We had to wipe it and reflash it, then recreate the rules. Now email is happy.

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